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P. R. Wycherley, O.B.E., B.Sc., Ph.D., F.L.S.

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981, pp. 1-4.

Ecosystem theory and management'

by A. R. Main

Zoology Department, University of Western Australia, Nedlands, WA 6009

Introduction

In Western Australia, and particularly in the
vicinity of Perth, man and his activities are producing
a serious impact on the remaining natural ecosystems
so that it is both prudent and desirable to intervene
and manage them in order that further undesirable
changes are avoided or reduced.

Adequate management of ecosystems requires a
prescription for action which has a basis in a theory
of how ecosystems function. However, ecosystems
are naturally so complex that it is necessary to dis-
sect them into component parts or processes for analy-
sis. Thus study may be devoted to the chronological
development of the ecosystem, or the diversity or
complexity of the ecosystem, or competitive rela-
tionships within a community, or community struc-
ture (producer/consumer or predator/prey interac-
tions). While these studies give insights into interac-
tions, they throw little light on processes operating
with communities which in turn are related to div-
ersity, complexity and stability. These lie at the core
of any understanding which can form the basis for
management. Recent studies emphasise the struc-
tural components of ecosystems, e.g. species, while
overlooking the other aspects of ecosystems, namely,
the processes involved, especially their role or func-
tion, and it is this aspect that I propose to emphasise
in the following brief development of a theory of
how ecosystems might be integrated, and then apply
the theory in a suggestive way to the local scene.

[n order to construct a general theory I propose to
take as a starting point the observation that life de-
pends on the fixation of nitrogen and the elaboration
of biologically complex molecules which can only be
done by a limited variety of organisms. Once elab-
orated, these molecules are a resource to be exploited
by organisms which cannot elaborate them. It is the
pattern of elaboration and exploitation that constitutes
the functional aspects of the ecosystem or community.
That is, the construction of the theory relies on a
biological approach which takes into account diver-
sity, complexity and stability which earlier I suggested
were near the core of understanding ecosystems.

Diversity

Taking the elaboration of biologically essential
molecules as a starting point, it is possible to conceive
or construct a hypothetical community in which the

1 Read at a seminar held at Murdoch University on 7 June
1980 as part of a series of meetings on the theme “Eco-
system management in Perth and its hinterland”.

biological molecules enter the system by way of syn-
thesisers and have a residual time in the community,
which is related as an

I synthesis, ] ^ + J biological \

input— dinitrification ->output— degradation!

[photosynthesisj ^

system. The nitrogen fixed and the molecules syn-
thesised are a resource to be exploited by organisms
unable to synthesise them themselves. Without the
interpolation of exploiting organisms a system could
be conceived of as producers and degraders (bacterial
decomposition). Without exploiting organisms the
system is at its simplest when the most vigourous and
actively reproducing and growing synthesiser out-
competes others for space and other resources. Diver-
sity of producers will be increased when a fluctuating
environment alternatively favours the fundamental
niche (Hutchinson 1957) of one or the other of the
synthesisers; or when exploiting organisms assume the
role of predators of the synthesiser, the predators being
favoured or not according to the way environmental
changes exceed or otherwise the possible states of per-
sistence defined by their fundamental niche; or when
competitive interactions delimit the realised niche of
some of the synthesisers or predators. By a com-
bination of these interactions it is possible to go on
packing the community with producers and con-
sumers until the resources of space, nutrients, and
biologically useful molecules can be divided no fur-
ther and still support an exploiting population.

In this sense the variety of consuming organisms
interpolated between the synthesisers and the de-
graders is a device for delaying the ultimate degrada-
tion of biological material by bacteria or increasing
the residence time before ultimate degradation.

Complexity

The basis of the community is nitrogen fixation and
the producers of biologically useful molecules, par-
ticularly amino acids and carbohydrates. The most
easily measured of these basic entities are those con-
cerned with trapped solar energy, that is, carbon flow.
However, the flow of biologically useful nitrogenous
compounds can be conceived as being of extreme
importance since nitrogen is essential for growth and
the nitrogen pool of the system could conceivably
be more limiting than any ability to synthesise carbo-
hydrates. The pool is of course replenished by nitro-
gen fixation, and in the Australian ecosystems there
may be anaerobic prokaryotes, photosynthesising pro-
karyotes, lichens, rhizobiai symbionts on legumes, or
actinomycete symbionts on other plants, e.g Cas-
uarina. Not all these routes of fixation operate all the

1

Journal of the Royal Society of Western Australia, Vol. 4. Part 1, 1981.

time: some are limited by seasonal conditions; others
are limited by serai stages in plant succession, e.g.
legumes in post-fire regeneration, or by the avail-
ability of decomposing litter as an energy source for
both aerobic and anaerobic nitrogen fixers.

Since the components of a community cannot grow
without amino acids and the nitrogen of the pool
depends on fixation, on the average at least replacing
that lost from the system by decomposition, then the
certainty that some nitrogen fixation will occur will
be related to the array of modes in the pathways of
nitrogen fixation.

The probability of persistence of the community
approaches 1 when the route or pathway diversity is
such that there will always be one mode operating
under all experienced variations of the environment.
Such a condition of diversity would define stability
with respect to the nitrogen needs of the ecosystem,
i.e. leaks from the system could be replaced by addi-
tion to the pool by fixation under all perturbing con-
ditions.

Mineral nutrients are also essential and often
limited in supply. Recycling of these nutrients in-
creases their retention time in the system. The pool
is replaced by release of pollen, flowering, fruit and
seed of deep-rooted plants which gather nutrients
from deep weathering profiles or from accumulations
of resulting downward leaching of soil solutes. Usually
there is more than one route for replenishment of the
mineral nutrient pool. In a post-fire situation the loss
of mineral nutrients from the system by run-off and
rainfall is minimised by the harvest by the root sys-
tem of freshly grown underground bulbs and tubers
and rhizomes or by shrubs with lignotubers or by
mycorrhizal fungi. Again there are a number of ways
for blocking leaks from the system. Leakage will be
least when the diversity of ways of gathering the
nutrients released in the post-fire situation is such that
at least one route will operate under any conceivable
post-fire situation.

In addition to the pathways of fixation there is a
tendency for nutrients to accumulate at their place of
origin or to fall into sinks, e.g. bogs, lakes, the water
table, or even in long-lived vegetation and deep-rooted
plants. Herbivores and predators can be looked upon
as devices for redistributing these nutrients.

In the sense used here, complexity has to do with
variety of modes in the pathways by which biologi-
cally important materials are introduced into the
system, the different modes of retention and storage,
and the ways in which they are redistributed.

Stability

In the foregoing examples diversity and complexity
have related to (i) maximising the retention time of
expensive biological molecules within a system, and
(ii) diversifying the number of modes in routes by
which the pool of biologically useful nutrients is
introduced into, retained, and redistributed within the
system so that a supply and retention is ensured under
all possible or conceivable circumstances.

In this sense the community that persists through
perturbations or disturbances is successful at achiev-
ing diversity in supply and retention and has thereby
achieved stability.

At any one instant of time one mode in a route
may be more important or efficient than another. At
such a juncture the inefficient routes are redundant
but stability on a long-term basis may in fact be
dependent on the retention of the redundancies. They
are in effect insurance policies. Efficiency of use of a
resource enhances the retention time by minimising
loss through the production of biologically useless
degradation products. However, as mentioned earlier,
over a long period of time “sinks” will appear within
a system and nutrients will accumulate there. Ulti-
mately there will be areas rich in nutrients and others
poor in nutrients. In the sense of preserving a com-
munity it is advantageous to delay this end, and we
can consider mobile animals as devices which delay
this end state. Animals such as chironomids or frogs
emerging from ponds or moth or other insect larvae
from trees or bees distributing pollen or mating
flights of ants or termites, or herbivores or predators
generally, are to be viewed as devices for delaying
the accumulation or redistributing important biologi-
cal substances.

Management

The problems of management range from the pro-
blems associated with natural communities which are
being distributed by being isolated as small reserves
or invaded by pathogen iPhytophthora) to the situa-
tions which are physically disturbed such as road
verges, or pits left by gravel extraction or bauxite
mining. In such disturbed places, a new community
may establish but it would take a long time. Nutri-
ents could be added and so hasten the establishment
of vegetation — but there is no feed-back if nutrient
supply is unbalanced. Moreover, from the theoretical
framework developed, the nutrients may have to be
replenished repeatedly if the community diversity and
complexity necessary for their retention is not present,
and replenishment is likely to be a costly and con-
tinuing process unless the natural input to the nutrient
pool can be balanced with the losses from the pool by
means of a suitably diverse and complex community.
Finally, stability will only be achieved when supply-
ing pathways are assured under all natural perturba-
tions.

Discussion

In the foregoing I have emphasised that diversity
of roles is essential so that retention times of nutri-
ents or replenishment of nutrient pools is maximised
under all possible circumstances. Establishment of
roles is hard work requiring a great deal of biological
insight. However, in addition to the well-known ability
of symbionts associated with legumes to fix nitrogen,
there is now an extensive and growing literature on
nitrogen fixation by plant associations other than with
legumes (Silvester 1977) as well as by free-living
microbes (Postgate 1971). Of particular interest is
the ability of actinomycete symbionts associated with
Casuarina to fix nitrogen. Actinomycetes appear to
be capable of establishing symbiotic relationships
with a number of woody shrubs (Silvester 1977) and
there may be as yet unrecorded symbioses among the
endemic woody shrubs. Shea and Kitt (1976) have
indicated the levels of nitrogen fixation by native
legumes, while Halliday and Pate (1976) have shown
that blue-green algae associated with Macrozamia are
capable of contributing nitrogen to their host.

2

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Peculiarities of the root systems of Australian Pro-
teacea have been studied for some time (Specht and
Rayson 1957, Purnell 1960). Lamont (1972a, b,
1973) has made a detailed study of the proteoid roots
of some Hakea species, while Lamont and McComb
(1974) have studied the role of microorganisms in the
formation of proteoid roots and Jeffrey (1967, 1968)
has implicated the importance of proteoid roots in
phosphorus nutrition.

Additionally fungi are being more and more impli-
cated as important components of ecosystems, both as
decomposers and in mycorrhizal associations (Hartley
1959, 1971). Moreover, mycorrhizas are associated
with eucalypts (Chilvers and Pryor 1965) and may
well be more widespread. Malajczuk et al. (1977)
have experimentally demonstrated the importance of
mycorrhizal infection. Mycorrhizas appear to be
important in increasing the area through which solutes
can be absorbed. They thus could have an important
role in retaining mineral nutrients within the ecosys-
tem, especially where soils are sandy and lack clays
on which nutrients might be absorbed and thus phy-
sically retained.

The foregoing suggests that natural history observa-
tions such as the invasion of gravel pits by Dryandra
rather than legumes or the invasion of disturbed
sandy areas or sand pits on the Swan coastal plain by
Adenanthos are in some way related to the role of
proteoid roots in nutrition. Likewise the ubiquity of
Casuarina species among the vegetation associations
growing on poor sandy soils could indicate the com-
mon mode of nitrogen fixation in the system.

Taken together the above suggest that in addition
to establishing the roles played by plant species we
need also to pay much more attention to the micro-
organisms of the soil, i.e. the rhizosphere, as well as
those that are symbionts on woody plants.

The identification of multiple modes in pathways
by which biologically useful materials are introduced
into a system, and an assessment of the conditions
under which each is optimised, have not been
attempted. Nevertheless if segments of the system
can be isolated, it is possible in theory to establish
measures of species diversity for the different path-
ways, and ideally measure the contribution of each
of these to the circulating pool of biologically import-
ant substances. Moreover, it may be possible to
establish the robustness of components of these path-
ways under perturbation. For example, when per-
turbations occur, there are a number of characteristic
sequences for regeneration, as already mentioned:
Proteacea (Dryandra) but generally not legumes in
gravel pits where soil and accumulated nutrients are
in poor supply, or legumes in burnt areas where,
depending on the intensity of the fire, nitrogen but
not minerals will be depleted. Perhaps these char-
acteristics in successional sequences are a manifesta-
tion of dominant pathways by which limiting nutri-
ents are being restored to the system.

Thus whilst diversity contributes to the retention
time of biologically expensive nutrients in an ecosys-
tem, it is likely that it is the multiplicity of modes in
pathways (duplications or redundancies) by which
biologically useful molecules are introduced into
(blue-green algae, lichens, free-living aerobic and
anaerobic microbes, symbiotic actinomycetes and
symbiont rhizobia) or retained within (fungi,

mycorrhiza, proteoid and other root systems, geo-
phytes and lignotubers which can rapidly produce an
extensive root system to scavenge and retain nutri-
ents) the ecosystem which is important for stability
of the system. The suggestion is that these redun-
dancies are such that in a stable system at least one
mode in each pathway will operate under the condi-
t.ons of perturbation natural to the system, and nat-
ural history observations may give a first clue to the
robustness of each mode.

The generalisation for the above example is that
under perturbations induced by gravel extraction
where depletion of soluble phosphorus is presumed,
the phosphorus replenishment mode by way of pro-
teaceous plants is robust, while the nitrogen mode by
way of leguminous plants is not. On the other hand,
following burning, when the phosphorus pool is intact
and the nitrogen pool depleted, the mode of nitro-
gen fixation by way of symbionts in legumes is
robust.

In a community disturbed by the invasion of Phyto-
phthora, or where any other cause of catastrophic
destruction of vegetation occurs, diversity and com-
plexity are destroyed and no mode in any pathway
persists, hence stability is lost.

Management should take into account these func-
tional roles of diversity and complexity, but it is
not likely to be easy to develop a complete data base
since so much of importance takes place in the rhizo-
sphere.

In summary, the theory developed is based on
functional integrity of the ecosystem rather than
specific components at any time. It has been assumed
that a system cannot sustain itself unless nitrogen
is fixed and minerals introduced into the system in
quantities which equal losses from the system. Should
these biologically important substances be in excess
of what the system can use they will be lost, i.e. the
system will leak. The presence of a substantial leak
suggests that there is an unexploited resource which
could be exploited by an organism new to the system.
Should this happen, the leak will be stopped and the
diversity of the system increased. The assumption is
that diversity increases until all serious leaks are
stopped.

In addition, the theory suggests that because en-
vironments fluctuate seasonally, and suffer other types
of perturbation and disturbance, only those persist
which contain a variety of modes in the pathways by
which biologically important substances are intro-
duced and retained within the system. The variety
of modes reflects the complexity of the system. Fre-
quently there are redundancies in modes but function-
ally the system retains its integrity and tends to return
to its former state after perturbations or disturbances.
It is the robustness of pathways which endows the
ecosystem with stability.

In terms of management of the ecosystem, the
compartments that appear to be important are those
devoted to the accession of nutrients; the synthesisers
(fixation of nitrogen, extraction of mineral nutrients
from deep profiles and photosynthesis); the redistri-
bution of nutrients (the animal component of the
ecosystem); and the organisms which maximise reten-
tion of nutrients within the system (fungi, mycorrhi-
zas and plant root systems generally).

3

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

References

Chilvers, G. A. and Pryor, L. D. (1965). — The structures of
Eucalyptus mycorrhizas, Aiist. Jour. Bot., 13:
245-259.

Halliday, J. and Pate J. S, (1976). — Symbiotic nitrogen fixa-
tion by coralloid roots of the cycad Macrozamia
reidlei: physiological characteristics and ecological
significance. Aust Jour. Plant Pliys.,. 3: 349.

Hartley, J. L. (1959). — The Biology of Mycorrhizas. Leonard
Hill, London.

Hartley, J. L. (1971). — Fungi in ecosystems. Jour. Ecol.,
59: 653-686.

Hutchinson, G. E. (1957). — Concluding Remarks, in Cold
Spring Harbour Symposia on Quantitative Bio-
logy, Vol. 22, p. 415-427.

Jeffrey, D. W. (1967). — Phosphate nutrition of Australian

heath plants. 1. The importance of proteoid roots
in Banksia (Proteacea). Aust. Jour. Bot., 15:
403-11.

Jeffrey, D. W. (1968). — Phosphate nutrition of Australian

heaths, M. Aust. Jour. Bot.,. 16: 603-13.

Lamont, B, (1973). — Factors affecting the distribution of pro-
teoid roots within the root systems of two Hakea
species. Aust. Jour. Bot., 21: 165-187.

Lamont, B. (1976). — Effects of seasonality and waterlogging
on the root systems of a number of Hakea
species, Aust. Jour. Bot., 24: 691-702.

Lamont, B. B, and McComb, A. J. (1974), — Soil microorgan-
isms and the formation of Proteoid roots. Aust.
Jour. Bot., 22: 681-8.

Malajczuk, N., McComb, A. J. and Loneragan, J. F. (1975). —
Phosphorus uptake and growth in mycorrhizal
and uninfected seedlings of Eucalyptus cala-
phylla R.Br. Aust Jour. Bot. 23: 231-238.

Postgate, J. R. (1971). — Fixation by free living microbes:
physiology, in J. R. Postgate (ed). The Chemistry
and Biochemistry of Nitrogen Fixation. Plenum,
London, p. 161-190.

Purnell, H. M. (1960). — Studies of the family Proteacea, 1.

Anatomy and morphology of the roots of some
Victorian species. Aust. Jour. Bot., 8: 38-50.

Silvester, W. B. (1977). — Dinitrogen fixation by plant associa-
tions excluding legumes, in R. W. Hardy and
A. H. Gibson (eds.) A Treatise on Dinitrogen fixa-
tion. Wiley, N. Y., London, p. 141-190.

Lamont, B. (1972a). — The morphology and anatomy of proteoid
roots in the genus Hakea. Aust. Jour. Bot.,
20: 155-174.

Shea, S. R. and Kitt, R. J. 0976). — The capacity of jarrah
forest native legumes to fix nitrogen. For. Dep.
West. Aust. Res. Paper 21.

Lamont, B. (1972b). — The effect of soil nutrients on the pro-
duction of proteoid roots by Hakea species.
Aust. Jour. Bot., 20; 27-40.

Specht, R. L. and Rayson, P. (1957): — The Dark Island Heath
(Ninety Mile Plain, South Australia), HI. The
root systems. Aust. Jour. Bot., 5: 103-114.

4

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981, pp. 5-11.

Peripheral vegetation of Peel Inlet and Harvey Estuary, Western Australia

by D. J. Backshall and P. B. Bridgewater

School of Environmental and Life Sciences, Murdoch University, Murdoch, W.A. 6153
Manuscript received 25 July 1979; accepted 27 November 1979

Abstract

Fifteen vegetation units, distinguished by differences in the floristic composition of vascular
plant species, have been recognised from the Peel Tnlet-Harvey Estuary system, Western
Australia. Analysis of the epontic diatom flora within units confirms their integrity. The
spatial distribution of these vascular-plant communities around the estuarine system appears
to be controlled by the substrate summer salinity values, together with the vertical distance
from the high water mark. Evidence from aerial photographs extending back 23 years
suggests that dynamic processes are less important than these spatial controls in determining
community distribution. Exceptions to this occur only when sudden major geomorphic
changes force concomitant vegetation changes.

Introduction

During 1977-78 an investigation was undertaken
of the peripheral vegetation and associated diatom
flora of the Peel Inlet-Harvey Estuary System, West-
ern Australia. This estuarine system comprises two
large shallow basins of 65 km^ (Peel Inlet) and
50 km^ (Harvey Estuary), joined to the sea by a
5 km inlet channel. The basins are connected to
each other by a narrow channel, which cut through
a broad, barely submerged marginal shelf. The sedi-
mentology of the area has been described by Logan
and Brown (1975). This survey was confined to the
tidal marsh environment of both Peel Inlet and
Harvey Estuary.

Ecological studies of Western Australian vegetation
have shown considerable methodological variation,
from empirical analysis of transects (e.g. Sauer
1964), classifications based on dominant strata using
a range of criteria (Gardner 1942, Speck 1952,
Beard and Webb 1974) to recent implementation of
numerical methods utilising floristic information
(Havel 1975). This paper outlines the application
of the Zurich-Montpellier (Z-M) method as a prac-
tical technique utilising floristic attributes. Addition-
ally, the paper evaluates the results from this tech-
nique with independently gathered environmental
data and data obtained from diatom sampling.

Theoretical implications of Z-M phytosociology
have been discussed by Bridgewater (1971), Westoft
and van der Maarel (1973) and Muller-Dombois and
Ellenberg (1974). These references contain the most
detailed accounts of the techniques available in the
English language, and it is not proposed to discuss
them further in this paper.

Methods

At each of eighteen sites (Fig. I) two or three
transects were laid from the high water mark to the
edge of the sandy beach ridge. These sites were

considered to represent the least disturbed examples
of a variety of soil and vegetational types. Soils
of the estuary fringe are referrable to three soil
systems — Bassendean and Spearwood Dune systems
and Pinjarra Plain soil system (McArthur and
Bettenay 1960). Site selection was made by field
reconnaissance, coupled with use of colour aerial
photography taken in 1976 by the Western Austra-
lian Lands Department. The transects comprised
regularly spaced releves (samples) one metre square
and spaced 5 or 10 m apart, depending on the
abruptness of vegetation change. A total of 747
releves were collected from the estuaries. Species
cover-abundance were recorded for each releve using
the Braun-Blanquet scale (Bridgewater 1971). A
set of computer programs was used to print tables
cf species and releves for each transect. These
tables were then examined, and ‘potential differential
species’ (PDS) noted. The initial choice of PDS is
made from species having an apparently clumped
distribution, with usually < 60% presence in the
group of releves forming the transect. Selection of
PDS was facilitated using a computer program,
which incorporates numerical methods as outlined
by Ceska and Roemer (1971). Groups of releves
with similar PDS were then extracted from the
transect raw tables and entered into a presence table
(Table 1).

Each column in Table 1 represents thus the sum
of a number of releves from the estuary, with the
frequency of species presence in these releves re-
corded as a percentage class (I-V). Table 1 allows
the structuring of a classification for the tidal marsh
vegetation (Table 2). As only one locality was
surveyed, it is inappropriate to utilise the standard
Z-M system of nomenclature. Accordingly, the
system of naming the vegetation units follows that of
Bridgewater (1974). For ease of reference all
specific names are derived from Blackall and Grieve
(1974) and Grieve & Blackall (1975).

5

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

The fifteen vegetation units derived from the
classification (Table 2), augmented by all diatom
species (Table 3), were subjected to Principal Axes
Ordination (van der Maarel 1969). This technique
allows a choice of reference stands which will establish
the extremes of a gradient instead of emphasizing
differences within the groups.

The ordination (Fig. 2) is accompanied by selected
substrate information. Summer salinity values were
derived from soil samples obtained from the top
10 cm of the soil profile. These were collected during
March from all transects, and analysed as a 1:5 soil
water extract using a P66 digital chlorodometer.
Total ions were measured as a 1:5 soil water ex-
tract using a Sproule electronic conductivity meter.
This analysis was performed in August. Data were

obtained from four replicate sites for each vegetation
group.

The Y axis of the ordination appears to relate
strongly to salinity, with hypersaline releves at the
positive end and slightly brackish releves at the
negative. The relationship of releves along the X
axis is less easily discernable, but approximates to
a littoral — beach ridge sequence.

Vegetation distribution and dynamics

Peripheral vegetation of an estuary is influenced by
marked variations in substrate conditions in both
space and time. Horizontal distance from the littoral
zone and vertical distance from a fluctuating water
table are two important factors superimposed on other
influences. Environmental factors may occur either
as a mosaic, or as an attenuating gradient, depending
upon local conditions. An understanding of the
spatial relationships of vegetation with these environ-
mental factors may help in elucidating temporal pro-
cesses operating within estuarine vegetation. Figure 3
shows the distribution of physical features, vegetation
units and salinity regimes along a hypothetical tran-
sect from water edge to established dunes.

Distribution of the Arthrocnemum complex com-
ponent communities reflect both spatial and temporal
sequences which are readily observed in numerous
salt marshes of the area. The Arthrocnemum bidens
community develops on the less saline rims of salt
marsh concavities, but progrades into the Triglochin
mucronata community at lower levels. In the more
saline centres of the concavities, A. halocnemoides
occurs as a single species, or in extreme environ-
ments, a bare pan develops. Where the concavities
are less saline, perhaps as a result of more effective
ground water or tidal flushing the Salicornia
qiiinqiieflora community occurs. Sedimentation of the
concavity and subsequent reduction of flushing im-
plies a maturation of the system through time. Where
the concavity is linked to the estuary, the Arthroc-
nemum complex merges with the Salicornia complex.

Beeftink (1962) found the salinity units of the
Venice system useful in environmentally classifying
saltmarsh communities. This system provides a classi-
fication of saline waters into three broad categories —
euhaline, with a range of 1.65-2.2% chlorinity,
polyhaline, with a range of 1.0-1.65% chlorinity, and
mesohaline, with a range of 0. 3-1.0% chlorinity.
Vegetation units 1-3 {Arthrocnemum complex) are
euhaline, using this terminology, while the Triglochin
mucronata and Salicornia quinqueflora communities
(units 4 and 5) are polyhaline, with all other com-
munities being mesohaline.

Many communities clearly respond to spatial
features, such as the salinity changes described
above, rather than temporal factors. Nevertheless,
due to the dynamic nature of shorelines in this
region, it is possible to infer some successional
relationships between communities. Inference may
be given a factual basis by comparison of old aerial
photographs with recent runs. In this study aerial
photographs from 1957 allowed a time scale to be
placed on some successional processes.

Initial development of tidal marshes can be linked
to emergence of spits or sandbars. Sedimentation
often continues until the bar is joined to the shore
by one extremity (Chapman 1938). Once sufficient

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Table 1.

Presence table for important species in the 15 vegetation units

Vegetation units (see Table 2)

1

2

3

4 ‘

5

6

7

8

9

10

11

12

i

i

13 i

1

14 1

15

Arthrocnenium halocnemoides

V

V

V

V

1

-1-

II

II

Salicornia quinqueflora

I

V

11

V

V

V

IV

V

HI

Suaeda australis

1

V

HI

+

HI

II

Juncus maritimus ....

111

IV

V

HI

I

V

Machaerina juncea

1

-t-

V

HI

Melaleuca raphiophylla

I

II

IV

HI

Schoenus fasicularis

1

IV

Apium prostratum ....

IV

Sporobolus virginicus

III

I

i

+

IV

IV

I

V

Atriplex paludosa . ..

I

I

V

V

Parapholis incurva ....

II

-1-

11

V

V

Cotula coronopifolia

V

IV

Arthrocnemum bidens

V

+

1

III

HI

Triglochin mucronata

-b

+

V

Gahnia trifida

-1-

V

+

II

+

Frankenia pauciflora

1

I

I

II

+

IV

1

Atriplex hastata

1

....

-f-

-f-

V

II

H

Polypogon monspeliensis ....

-f

-1-

I

III

11

V

V

Angianthus preissianus

I

I

III

-1-

IV

Casuarina obesa

I

III

11

I

I

I

I

Hordeum hystrix

■1-

HI

+

II

Melaleuca cuticularis

-f

I

II

III

HI

II

I

Samolus juncea

-j-.

111

-U

HI

11

II

Note: I = species occurred between 0-19% of releves taken.

II = species occurred between 20-39% of releves taken.

III = species occurred between 40-59% of releves taken.

IV = species occurred between 60-79% of releves taken.

V = species occurred between 80-100% of releves taken.
+ = species occurred in only one releve taken.

N.B. Species which occurred in less than 5 of the total releves are not included in this table.

protection is afforded, the pioneer community appears
to be the Salicornia quinqueflora community, often
with S. quinqueflora as the only species represented.
As the surface is stabilised, and raised a little by
silt accumulation, the Salicornia community is re-
placed by the Salicornia-Suaeda australis community,
A tidal marsh of these two communities now exists
north of Heron Point, Harvey Estuary. That this
marsh has developed within 20 years is established
by comparison of aerial photographs for 1957 and
1976.

Marshes colonised by Arthrocnenium species are
more saline, tend to be completely summer dry and
certainly have a better developed soil profile than
the early colonising spits and sandbars. It seems
likely that the Arthrocnenium community represents
a stable environment, which could be regarded as
climax vegetation. Most of the communities identi-
fied appear more correlated with estuarine and
fluvial processes, rather than the base soil system.
Exceptions to this appear to be the Salicornia-
Machaerina and Schoenus-Sporobolus communities
which are apparently confined to shores of the
Spearwood Dune system.

Diatom communities

Little work has been done in Australia on the
diatom flora of estuaries and salt marshes, with
Wood (1964) being the most significant contribution.
Diatoms form an important part of the food chain in
estuaries, with some species also useful as environ-
mental indicators. Associations of distinct diatom
communities with terrestrial and macro-algal com-
munities in salt marshes and estuaries have been
noted by Carter (1948), Round (I960) and Chap-
man (1962).

Table 2.

Classification of vegetation units

I. Arthrocnenium halocnenioides complex

1. Arthrocnenium bidens community

2. A. halocnemoides community

3. Salicornia quinqueflora community

4. Triglochin mucronata community

II. Salicornia quinqueflora complex

5. S. quinqueflora community

III. Salicornia quinqueflora — Suaeda australis complex

6. Suaeda australis community

IV. J uncus maritimus — Salicornia quinqueflora complex

7. Cahnia trifida community

8. Junciis maritimus — Salicornia quinqueflora com-

munity

V. Salicornia quinqueflora — Machaerina juncea complex

9. Salicornia quinqueflora — Machaerina juncea com-

munity

VI. Schoenus fasicularis — Sporobolus virginicus complex

10. Schoenus fasicularis — Sporobolus virginicus com-

munity

VII. A triplex paludosa complex

11. Frankenia pauciflora community

12. Atriplex hastata community

VIII. Juncus maritimus complex

13. Juncus maritimus community

IX. Cotula coronopifolia — Parapholis incurva complex

14. Polypogon monspeliensis community

15. Sporobolus virginicus — Angianthus preissianus

community

Vegetation units denoted by arable numerals refer to the
numbered columns in Table 1,

7

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

y

9

36 /^

74

36

79

51

^1

06

28

11

12

30

30

15

15

36 ; 10

5

/

12

/

/

/

/

/

f-

\

15 '^9

14

13 19 /

'l2

Figure 2. — Principal Axes Ordination of the 15 vegetation units. Figures in bold type represent vegetation units, (see Table 2).
Figures in lighter type represent values for chlorinity and total ions (Meq. L-i//iMhos x 10'2). Dashed lines define salinity,

where E equi.ls euhaline, P equals polyhaline and M equals mesohaline.

Figure

salinity

3 —Schematic diagram of important physical features of the peripheral estuarine environment, vegetation units and
tvres along a hypothetical transect. Figures denote the vegetation units, while the salinity types are indicated thus:
M equals mesohaline, P equals polyhaline, E equals euhaline.

8

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Diatom communities and floristically defined vascular
plant communities may well be affected by different
environmental conditions. Aleem (1950), however,
showed that benthic diatoms seldom penetrate deeper
than 2 mm into the marsh surface. Diatoms form
a micro-habitat of mucilage on the surface of salt
marshes in the Peel-Harvey system, so they could
be buffered to some extent from the high salinity
levels in the soils of the mature marshes. Plank-
tonic forms may also be temporarily deposited in
benthic conditions, and, if sampled, could con-
ceivably affect the results obtained. With these

caveats in mind, an analysis of diatoms found in
each of the 15 vegetation units was attempted.

Four widely distributed replicate sites were chosen
for each of the vegetation units noted in Table 2.
Soil surface scrapings from each site were cultured
in petri dishes in the laboratory. A sterilised solution
of sugar and yeast extract was applied as required,
to keep the scrapings moist for a period of three
weeks before being examined. In this way, species
dormant in the soil were encouraged to become
active and more readily observed.

Table 3.

Diatom species located in vegetation units

Vegetation units (see Table 2)

Achnanthes longipes Agardh

Mastoglia ignorata Hust

Amphora javanica A.S

Navicula marina Ralfs in Pritchard

Cocconeis speciosa Gregory

Nitzchiasp.6

N. longissima (de Brebisson ex Kutz) Ralfs in Pritchard

Diploneis crabro

Nitzchia subvitrea .

Diploneis sp. 1

Nitzchia vitrea Norm

Cymbella subturgidaWnst.

Navicula sp. 1

Cocconeis distans A.S

Nitzchia sigma var. rigida Grun. ex Van Heurck

Achnanthes sp. 2

Amphiprora angustata H^cndey

Achnanthes sp. 3

Opephora sp. 1

Synedra sp. 1

A nomoe ni s sp. 1

Genus A

Plagiogramma sp. 1

Nitzchia closterium (Ehr.) Wm. Smith

Amphora gigantea Grun. \n A.S.

Genus B
Mastoglia sp. 2

M. pseudoparadoxia Hust.

Navicula sp. 2

N. vulpina Kutz

Fragillaria sp. 1

Nitzchia gracilis Hsintz

TV. sp. 4

(de Brebisson) Cleve

Nitzchia sp. 1

Navicula elegans Smith

Nitzchia brebissonii y/m. Smith ....

N. sp. 5

Amphora proteus Gregory
Achnanthes brevipes Agardh
Amphora macilenta Gregory
Cocconeis scutellum Fhr. ■ ..

Thalassothrix sp. \ ...

Cocconeis debesi Hust

Epithemia sp. I

Cocconeis apiculata A.S

Navicula sp. 3

Nitzchia compressa (BaW.) ^oyer
Pleurosigma strigosum 'Nm. Smith
Epithemica sp. 2
Achnanthes sp. 1

Grammatophora macilenta Wm. Smith ...

Pinnularia legumen Ehr

P. splendida Hust. . .

Cocconeis placentula Ehr.

Navicula lyra var. elliptica A.S

Pinnularia ambigua Cleve . .

Amphora graeffii (Grun.) Ci

A. sp. 2
Nitzchia sp. 2

N. sp. 3

Melosira sp. 1
Cymbella yarransis A.S.Ci.

Genus C
Cocconeis sp. I

Grammatophora marina (Lyngb.) Kutz , .

9

Journal of the Royal Society of Western Australia, Vol. 4. Part 1, 1981.

Where species identification was not possible a
code name was used. Descriptions and drawings of
unidentified diatoms may be found in Backshall
( 1977). or copies may be acquired from the authors.
Identification of species was achieved using
the following works: Crosby and Wood (1959),
Wood et al. (1959), Wood (1961a, 1961b, 1963)
and Hendey (1964).

The distribution of diatoms (Table 3) shows that
more than 50% of the species were unique to in-
dividual vegetation units, although approximately
half of these were accounted for by groups 1, 5, and
6. Unique species present in groups 2 and 4 add
justification for distinguishing these vegetation units.
Groups 10, 11, 14, 15 are, however, distinguished
only by their paucity of diatom flora. This is
probably a reflection of long periods of surface
desiccation on these more elevated sites. Nitzchia
compressa, Cocconeis placentula, Pinniilaria legiunen
and P. splendida indicate some affinity between
groups 1 and 6. The Arthrocnemum bidens com-
munity (group 1) is typically found on the emerg-
ing fringes of salt marsh concavities, while Scdicor-
fiia-Suaeda community (group 6) occupies a similar
zone on the emerging banks of the estuaries. The
suggested similarities may be because the communi-
ties occupy sites of regular water fluctuation while
differences in salinity of these 2 habitats appear to
be reflected by differences in the diatom flora of
the communities. Similarly, although the Saliconiia-
Siiaeda community and the Saliconiia quinqiiefiora
community may have unique species of diatoms, a
clear relationship between them is indicated by the
common presence of Amphora proteus, Nitzchia
sp. 5, Cocconeis scutellum, Achnanthes brevipes,
Amphora macilenta and Thalassiothrix sp. 1. Both
vascular-plant communities are found at similar
elevations above high water mark, but with different
soil salinities.

The overall distribution of diatom species is
similar to that reported by Round (1960) with many
species exhibiting a strong preference for different
habitats, while others demonstrate a wider tolerance.
Lack of the common planktonic genera Rhizosolenia,
Chaetoceroiis and Coscinodiscus would seem to con-
firm that the species encountered are indicative of
surface changes, rather than planktonic drift-ins.

Interaction of peripheral and submerged vegetation

One of the major environmental problems in the
Peel-Harvey system is high productivity of the alga
Cladophora. During winter storms massive amounts
of algal material are deposited on shorelines, often
with severe results on the Jiuicus maritimus com-
plex. Massive deposition can cause death or debili-
tation of the Jimcus and consequent erosion. Coloni-
sation of the large masses of Cladophora is often
effected by Atriplex spp. and Siiaeda australis. This
latter species commonly colonises organic deposits,
e.g. Zostera deposits at Westernport Bay, Victoria.

At some points on the shores of Peel Inlet Scirpus
maritimus appears to also colonise areas of light
Cladophora deposition. There appears to be a com-
petitive interaction between S. maritimus and J.
maritimus on these sites which warrants further
investigation. Degradation of the established Juncus

maritimus community will inevitably result in shore-
line regression, and consequent build-up of silt in
other sites.

This effect is another problem associated with the
occurrence of Cladophora mats. Regeneration of the
shoreline appears rapid in regions where the Sali-
cornia quinqiiefiora — Suaeda australis community
occurs (i.e. in areas where shoreline stabilization
is proceeding naturally), but is lacking on the eastern
shore of Peel Inlet. The introduction of colonising
species (e.g. Suaeda australis, Atriplex hastata) ,
into freshly deposited Cladophora mats could be a
useful management tool in preventing erosion, and
aiding rapid assimilation of the Cladophora.

Acknowledsements . — Thanks are due to Mr. J. Johns for
assistance with diatom taxonomy, and Mr. P. Wilson for
discussions on the Chenopodiaceae of the south-west. Dr. R.
Fields provided valuable background data for the study
area. Special thanks are due to Ms. K. Gom and Ms. J.
Jolly for typing and cartographic assistance.

References

Aleem, A. A. (1950). — The diatom community inhabiting mud-
flats at Whitstable, Kent. New PhytoL, 49 :
174-188.

Backshall, D. J. (1977). — The Peripheral vegetation of the
Peel-Harvey Estuarine system. Unpublished B.Sc.
Honours thesis, Murdoch University.

Beard, J. S. and Webb, M. J. (1974). — Vegetation Survey of
Western Australia: Great Sandy Desert — Part I
Aims, objectives and methods. University
Western Australia Press, Perth.

Beeflink, W. G. (1962). Conspectus of the phanerogamic
salt plant communities in the Netherlands. Biol.
Jaarboek Dodonacea, 30 : 325-362.

Blackall, W. and Grieve, B. J. (1914).— How to know Western
Australian Wildfiowers. Parts I, II, III, University
Western Australia Press, Perth.

Bridgewater, P. B. (1971). — Practical applications of the
Zurich system of phytosociology. Proc. Row Soc.
Viet., 84: 255-262.

Bridgewater, P. B. (1974). — Peripheral vegetation of Western-
port Bay. Proc. Roy Soc. Viet., 87: 69-78.

Carter, N. (1948). — A comparative study of the algal flora
of two salt marshes. J. Ecol.,. 20 : 341-70.

Ceska, A. and Roemer, H (1971). — A computer program
for identifying species — releve groups in vegeta-
tion studies. Vegetatio, 23: 255-277.

Chapman, V. J. (1938). — Studies in salt marsh ecology. J.
Ecol., 26: 144-179.

Chapman, V. J. (1962). — The Algae. MacMillan Press,
London.

Crosby, L. H. and Wood, E. J. F. (1959).— Studies of
Australian and New Zealand diatoms. II. Nor-
mally Epontic and Benthic genera. Trans Roy.
Soc. N.Z., 86: 1-58.

Gardner, C. A. (1942). — The vegetation of Western Australia
with special reference to climate and soils. J.
Roy. Soc. West Aiisf.. 28.- xi-lxxxvii.

Grieve, B. J. and Blackall, W. (1975). — How to Know Western
Australian Wildfiowers. Part IV, University
Western Australia Press, Perth.

Havel, J. J. (1975). — Site-vegetation mapping in the northern
Jarrah Forest (Darling Range). 1. Definition of
site-vegetation types. W.A. Forests Department
Bulletin 86.

Hendey, N. I. (1964). — An Introductory account of the smaller
algae of British Coastal Waters. Fishery Investi-
gations, Series IV. H.M.S.O. London.

Logan, B. W. and Brown, R. G. (1975). — Interim report on
investigations of the sedimentology of Peel and
Harvey inlets. Mimeo. Geology Dept., University
Western Australia, Perth.

Maarel. E. van der (1969). — On the use of ordination models
in Phytosociology. Vegetatio, 22: 275-283.

10

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

McArthur. W. M. and Bettenay, E. (1960). — The development
and distribution of the soils of the Swan coastal
plain, IVestern Australia. CSIRO Australian Soil
Publication, 16.

Muller-Dombois, D. and Ellenberg, H. (1974). — Aims and
Methods of Vegetation Ecology, Wiley, New York.

Round, F. E. (I960). — The diatom flora of a salt marsh on
the River Dee. New PhytoL, 59; 332.

Sauer, J. (1%4). — Geographical reconnaissance of W.A. sea-
shore vegetation. Aust. J. Bot., 13; 39-69.

Speck, N. H. (1952). — The ecology of the metropolitan sector
of the Swan Coastal Plain. M.Sc. Thesis. Uni-
versity of Western Australia.

Westhoff, V. and Maarel, E. van der (1973). — The Braun-
Blanquet approach. In Handbook of Vegetation
Science, V, Classification and Ordination. (Ed.
R. H. Whittaker), 617-726. W. Junk, den Haag.

Wood, E. J. F., Crosby, L. H. and Cassie, U. (1959). —
Studies on Australian & New Zealand diatoms.
III. Descriptions of further discoid species. Trans.
Roy. Soc. N.Z., 87: 211-219.

Wood, E. J. F. (1961a). — Studies on Australian & New Zea-
land diatoms. IV. Descriptions of further seden-
tary species Trans. Roy. Soc. N.Z., 88: 669-698.

Wood, E. J. F. (1969b). — Studies on Australian & New Zea-
land diatoms. V, The Rawson collection of
recent diatoms. Trans. Roy. Soc., N.Z., 88: 699-
712.

Wood, E. J. F. (1963). — Studies on Australian & New Zea-
land diatoms. VI. Tropical & subtropical
species. Trans. Roy. Soc. N.Z.,. 90: 190-218.

Wood, E. J. F. (1964). — Studies in microbial ecology of the
Australasian region. Nova Hedwigia,. VIII; 453-
568.

11

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Obituary

Leslie William Samuel 1908-1980

L. W. (Les) Samuel, former Director of the
Western Australian Government Chemical
Laboratories, died on 20 July 1980. He was
educated at Perth Modern School, the University
of Western Australia and the University of London
and was one of the many Modern School students
of that era to become prominent in the professional
life of the State.

After graduating B.Sc, he worked for a short
period in the Department of Agriculture under Dr.
L. J. H. Teakle on soil surveys, before obtaining
a Hackett Studentship in 1933 to do a Ph.D. at
the University of London. His supervisor at London
University was Sir John Russell, Director of
Rothamsted Experimental Station, who wrote to
the Chancellor of the University of Western
Australia saying "We found Samuel to be a diligent
and capable investigator, a good manipulator in the
laboratory and a clear thinker in seeking interpreta-
tion of his results”.

Returning to the Western Australian Department
of Agriculture in 1935 he became a cereal chemist
and for many years was a judge of bread at the
Perth Royal Show. In 1947 he became Deputy
Government Agricultural Chemist in the Govern-
ment Chemical Laboratories and was promoted to
Director in 1957, in which position he remained until
his retirement in 1973. During his seventeen years as
Director he considerably increased the influence
of the Laboratories in the community.

He was a man who lived for his work and in
all his 40 years in the State Public Service, he
took only a months long service leave and very little

of his annual leave. His ability as a clear thinker,
perceived early by Sir John Russell, remained with
him all his life. His scientific approach and
integrity, and his ability to be nearly always right
won him the respect of those with opposing views,
even if many did not appreciate being proved
wrong. He was a strong supporter of his profession
and joined the Royal Australian Chemical Institute
as an Associate in 1930. He was made a Fellow in
1948 and was honoured further by being elected a
Fellow of the Royal Institute of Chemistry.

He joined the Royal Society of Western Australia
in 1931 and served on the Council from 1957-1969.
He was elected an Honorary Life Member in 1977.
Although an active worker for the Society on
sub-committees and as Hon. Auditor for more
than 20 years he declined to take the office of
President. Dr Samuel was a Fellow of ANZAAS
for many years and was a foundation member of
the Australian Institute of Agricultural Science.
He worked actively for these organisations, but
again declined to hold any executive positions.

Les Samuel will long be respected and remembered
by his friends, colleagues and associates, and many
scientific organisations will be the poorer without
his penetrating comments and constructive

criticisms.

R.C.G., C.F.H.J.

12

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981, pp. 13-16.

Preliminary observations of behavionral thermoregnlation in
an elapid snake, tbe dugite, Pseudonaja affinis Gunther

by H. Saint Girons* and S. D. Bradshaw

Zoology Department, University of Western Australia, Nedlands, W.A. 6009.
(*Laboratoire d'Evoliition, Universite de Paris VI, 105 boulevard Raspail, Paris 75006, France.)

Manuscript received 18 September 1979; accepted 19 February 1980

Abstract

Biotelemetry was used to study the behavioural thermoregulation of an adult dugite
(Pseudonaja affinis) which was confined in a large external enclosure. At the start of
digestion the dugite regulated its body temperature at 32.9 ± 0.21 °C and this fell within
a few days to 32.2 ± 0.09°C (p < 0.01) which appears to correspond to the range for the
preferred body temperature (PBT) for this species. Throughout the period of observation
the snake periodically allowed its body temperature to rise above the PBT, when exploring
the enclosure or searching for food, and this often exceeded 34°C with 35.4*"C being the
maximum temperature voluntarily tolerated. As periods of thermoregulation and searching
alternated throughout each day, the overall mean body temperature recorded was higher
than the PBT and equalled 33.6 ± 0.23'’C at the start and 32.4 ± 0.12°C at the end of
the period of digestion.

Introduction

Studies of behavioural thermoregulation in reptiles
have concentrated almost exclusively until recently on
lizards (see Templeton 1970 for a review) but the
development of suitable biotelemetric techniques has
resulted in an increasing number of studies devoted
to snakes (McGinnis and Moore 1969, Osgood 1970,
Johnson 1972, Naulleau and Marques 1973, Bui Ai
et al. 1975, Saint Girons 1975, 1978, Shine 1976).
However, information on the thermal preferences of
Australian elapid snakes is extremely meagre and
fragmentary (see Heatwole 1976 for a bibliography)
and this motivated us to make some preliminary
observations on a single large specimen of the
dugite (Pseudonaja affinis) held in captivity in Perth,
Western Australia.

Materials and methods

The observations were carried out on an adult
male dugite (Pseudonaja affinis) captured on 9 No-
vember 1978 at the University of Western Austra-
lia’s Marsupial Breeding Station at Jandakot. The
snake was placed the next day in a large enclosure
(3.5 X 2.5m) which had a sand base and was
furnished with a variety of stone shelters and two
large basins containing water. The enclosure was in
the shade of surrounding trees each day between
0800 and 0855 h and from 1430 h onwards. Another
smaller dugite and two tiger snakes (Notechis ater),
all captured on the same day at Jandakot, were
also housed in the same enclosure. On 16 November
the large dugite, which had settled down well in
the enclosure and was no longer disturbed by the pre-
sence of observers, swallowed at 1045 h a dead mouse
containing a temperature-sensitive radio transmitter
(Model V, Mini-Mitter Co. Tnc., Portland, Oregon).
The dugite ate a second mouse at 0900 on 17 No-

vember and the observations were terminated at
1800 h on 20 November. The dugite was encouraged
to regurgitate the transmitter by gentle manipulation
and at this stage the second mouse was almost
completely digested.

The transmitter was calibrated in water with a
Schultheis thermometer, before and following its
implantation in the dugite. The pulse rate varied
linearly between 0°C and 50°C and the signal was
received with a small commercial transistor radio.
The number of pulses per 30 seconds were counted,
using a stopwatch, and subsequently converted to
give the body temperature of the animal. The trans-
mitter used had a useful range of approximately Im
and antennae were placed on the ground inside the
enclosure to facilitate reception of the signal when
the dugite was moving about. In total, 181 measure-
ments of the body temperature of the snake were
recorded, 128 of these on 18 and 19 November
when the animal was kept under continuous obser-
vation. Mean temperatures were calculated from
the values recorded when the enclosure was in full
sunlight and the animal was thus provided with a
suitable gradient for thermoregulation. Data from
periods when the enclosure was in shade are shown
in Figure 1, but were excluded when calculating
mean body temperatures.

The statistical significance of differences between
mean body temperatures was assessed using Student’s
t-test and a probability of less than 0.05 was taken
to indicate significance.

Results

The dugite emerged from its nocturnal shelter as
soon as this was touched by the first rays of sun-
light in the morning (at approximately 0715 h)

13

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Figure 1. — Body temperature throughout the day of a large male dugite (Pseudonaja affinis) confined in an external enclosure
on (A) 18 November 1978 and (B) 19 November 1978. The arrows { v’ ' ) indicate the times between which the

enclosure was in full sunlight and the animal was thus provided with a large thermal gradient: (====) period when

the snake was in its shelter; ( ) periods when the snake was engaged uniquely in thermoregulatory behaviour;

( ) periods when the snake actively explored the enclosure in search of food

with a body temperature between 18°C and 22°C,
depending upon the day. During most of the time
when the sun was shining the animal was engaged
in thermoregulatory activity, either resting in the
shade or exposing a variable portion of its body to
the sun’s rays, usually at the entrance to its shelter.
Under these conditions the body temperature did
not vary by more than 3.6°C, the preferred body
temperature (PBT) being 32.9 ± 0.30°C on 17
November, the day after swallowing a mouse, and
this fell to 32.2 it 0.37°C by 20 November by
which time the process of digestion was much more
advanced, the difference between these two means
not being statistically significant (see Table 1). If
however one compares the pooled mean for Novem-
ber 16 and November 17 (32.9 ± 0.2 1°C) with the
overall mean for November 18-20 (32.2 di 0.09°C),
thf;n this decline is statistically significant with

p < 0.01.

Shade from nearby trees fell over the enclosure
by 1430 h each day and the snake always returned
to its shelter by 1500 h. Subsequently it would
emerge infrequently and then only for brief periods
in the late afternoon. At different periods of the
day, usually between 0730 h and 1000 h and between
1300 h and 1500 h, the dugite would actively explore
the enclosure attempting to burrow beneath all the
stones and water containers. These activity periods.

which were apparently motivated by a search for
food, could be set off at any time of the day simply
by the odour of a dead mouse and were observed
at body temperatures ranging from 26.0°C to 34.9°C.
During these periods the snake did not attempt to
regulate its body temperature which consequently
increased rapidly when the animal was in full sun-
light up to a temperature of 35.4°C which corres-
ponded to the maximum voluntarily tolerated. On
reaching this temperature the animal would either
move into the shade or, more often, return to its
shelter whereupon its body temperature would fall
rapidly, generally to a level much lower than the
PBT, as if to compensate for the period of over-
heating. Only later would the dugite re-emerge parti-
ally and resume its normal thermoregulatory be-
haviour. Figure 1 gives a number of clear examples
of such behaviour.

During nine such exploratory periods observed be-
tween 16-19 November, the mean body temperature
of the dugite fell four times between 34.5 and 35.0®C
and the mean recorded for the other five periods
were respectively: 35.2°C, 34.3“C, 33.9°C, 32. DC
and 26.7°C. From these observations it would ap-
pear that such exploratory or food-seeking behaviour
in the dugite is reasonably temperature-independent
between the maximum voluntarily tolerated (35.4°C)
and some minimum temperature which is probably

14

Journal of the Royal Society of Western Australia, Vol. 4. Part 1, 1981.

Table 1

Mean body temperatures (’’C) and range for the dugite, Pseudonaja affinis, during periods of exclusive thermoregulation {PBT) and overall,

inc luding exploratory and food-seeking, behaviour.

Date

Preferred Body

Range

Overall Mean

Range

(1978)

Temperature (PBT)

Body Temperature

1 6 Nov.

32-8 ± 0 - 15 (5)

32 -3-33 -2

33-7 ± 0-34 (10)

32-3-35-4

17 Nov.

32-9 ^ 0-30 (12)

31- 1-34-4

33-5 + 0-31 (17)

31-1-35-4

18 Nov,

32-4 0-67 (25)

31 • 1-33-2

32-8 0-19 (40)*

29-6-35-4

19 Nov.

32- 1 ± 0-95 (47)

29-6-33-5

32-3 ± 0-18 (64)**

28-0-35-4

20 Nov.

32-2 ± 0-37 (11)

31-5-32-9

32-2 0-37 (1 1)*

31 -5-32-9

Data given as mean ± S.E., number of observations in parentheses. Statistical significance of differences between
means are given relative to the mean on the first day (16 November 1978) with * p < 0 05 and ** p < 0 005.

lower than 26°C. Such activity is limited nevertheless
by the rapidity with which the animal attains its
maximum temperature voluntarily tolerated during
sunny periods of the day and this renders such ex-
ploratory activity virtually impossible during the
hottest periods of the day, even in spring.

Since the body temperature tended to rise towards
the maximum voluntarily tolerated whenever the
animal was active and searching, the overall mean
of all the body temperatures recorded when it was
possible for the dugite to thermoregulate is almost
certainly higher than the PBT. This overall mean was
33.6 ± 0.23 '’C for 16-17 November and 32.4 zb 0.12°C
from 18-20 November (see Table 1), the difference
between the two means being statistically significant
with p < 0.001. The average PBT calculated at the
beginning of the period of digestion (16-17 No-
vember) was 32.9 it0.21°C and 32.2 dz 0.09°C over
the period 18-20 November, when the period of
digestion was more advanced, the difference between
these two means being statistically significant with
p < 0.005.

Discussion

In their now classic study of the behavioural
thermoregulation of desert reptiles, Cowles and
Bogert (1944) recognised a “basking range”_ and a
"normal activity range” falling between the minimum
and maximum temperatures voluntarily tolerated.
Within the normal activity range they identified a
"preferred” body ternnerature (PBT) for each species,
which they also called the optimum or “eccritic”
body temperature, corresponding to the mean of
the body temperatures recorded when the animal
is provided with a sufficiently extensive temperature
gradient. Subsequently, many workers (e.g. Bratt-
strom 1965) have tended to confuse this PBT with
the average body temperature of animals captured
randomly throughout the day in the field, and taken
usually with little regard for the specific behaviour
of the animal at the time. Heath (1964) and Licht
ei al. (1966) where amongst the first to point out
that such average body temperatures are misleading,
comprising as they do, measurements from animals
involved in a variety of activities, including basking
when the body temperature has not yet attained the
PBT. In many cases, although the animals may be
active, the prevailing conditions may also be such
that it is impossible for them to attain their PBT
and Licht et al. (1966) and Bradshaw and Main
(1968) noted a number of discrepancies between
such field body temperatures and the temperature

chosen by the same animals in a photothermal gra-
dient in the laboratory. The problems associated with
the measurement of the PBT are now better appreci-
ated and have been recently discussed in the litera-
ture (see Saint Girons 1975, Heatwole 1976, Werner
and Whitaker 1978).

In the case of Pseudonaja affinis, it is clear that
so long as the snake is provided with a sufficiently
broad thermal gradient it will maintain its body
temperature within relatively narrow limits and the
PBT of the animal studied varied little over a period
cf five days, being approximately 33 °C at the
beginning of digestion and 32°C at the end.
The minimum temperature voluntarily tolerated is
almost certainly lower than the lowest temperature
recorded during the study (18°C) and the normal
activity range for the dugite would appear to be
between 26“C and 35.4'’C, the latter representing
the highest temperature voluntarily tolerated by this
individual. Obviously the study of further individuals
will modify this range somewhat but the above are
probably reasonable estimates of these parameters
for this species. The temperature range is very
close to that of Coluber flagellum (Masticophis
flagellum), a diurnal Colubridae living in compar-
able semi-arid regions of the Mediterranean, for
which Cowles and Bogert (1944) found a normal
activity range from 27 to 35°C, a PBT of 33°C and
a maximum temperature voluntarily tolerated of
37 °C. Other specific comparisons are difficult to
make, because of the variety of techniques ernployed
by various workers and the frequent confusion be-
tween the PBT and the average field temperature of
active animals, but it would appear that diurnal
colubrids and elapids such as Coluber flagellum and
Pseudonaja affinis, which actively hunt their prey in
hot arid and semi-arid environments, have relatively
elevated PBTs falling between 32 and 34°C (e.g.
Salvadora exalepis, Jacobson and Whitford 1971,
Pseudonaja textilis, Witten 1969). The rest of the
Colubroidea, regardless of whether they are species
from temperate regions, which are invariably diurnal
and heliothermic no matter what their mode of life,
or species such as the desert vipers which move
mainly at night and surprise their prey, have a
PBT between 30 and 32.5‘^C ((7owles and Bogert
1944, Saint Girons and Saint Girons 1956, Witten
1969, Shine 1976, Spellerberg and Phelps 1975, Heat-
wole 1976, Saint Girons 1978). The temperature
preference of the Natricinae living in temperate
regions appear to be even lower with PBTs falling
between 27 and 30°C (Stewart 1965, Kitchell 1969,
Osgood 1970, Gehrmann 1971). The few data

15

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

published on snakes living in intertropical forests,
most of which are not heliothermic, are difficult
to interpret at this stage but it seems likely because
of the high nocturnal temperatures characteristic of
this environment that they also have low PBTs,
as is the case with lizards inhabiting the same
biotope (Ruibal and Philibosian 1970).

When they are preoccupied with activities such as
food-seeking or courtship, heliothermic reptiles
abandon to some extent their habitual precise thermo-
regulation. The minimum temperature voluntarily
tolerated under these circumstances varies somewhat
according to the type of activity in which the animal
is engaged and can differ considerably from that
measured for example at the beginning of the bask-
ing period. The maximum temperature voluntarily
tolerated on the other hand appears to represent
for the animal an upper physiological limit which
cannot be exceeded, no matter what the activity. In
temperate regions, exploratory behaviour or food-
seeking is usually accompanied by a progressive
fall in the body temperature to below the PBT
whereas the reverse is the case with snakes living
in hot arid regions which already have a PBT
close to the upper limit of the normal activity
range, and usually only a few degrees away from
the maximum temperature voluntarily tolerated.
This “overheating” during periods of more intense
activity is particularly clear in the case of Pseudonajci
affinis and, as a result, the mean body temperature
of the snake during the sunny hours of the day was
often as much as 1C° above the animal’s PBT.
It is possible that the rather high mean body tem-
perature reported by Webb (1973, cited by Shine
1976) for the snake Pseudonaja texliUs in an outdoor
enclosure is due to the same phenomenon.

It is well established that European vipers, and
probably the great majority of snakes, display thermal
compensation when necessary. For example, during
days with intermittent sunshine, vipers will manage
to attain their PBT by a series of long basking
periods in which they allow their body temperature
to rise, almost to the maximum voluntarily tolerated,
following periods of forced cooling when the sun is
obscured by cloud (Saint Girons 1975). In hot
regions this form of thermal compensation obviously
functions in the opposite sense. Thus, after a period
of exploration during which the body temperature of
Pseudonaja affinis would rise to over 35°C, the snake
would return to its shelter and allow its temperature
to fall below 30°C before recommencing normal
thermoregulation. It is also possible that this habitual
exposure to elevated body temperatures permits
arid-living species such as the dugite to retain a
relatively low PBT, which is only of the order of
1 or 2C° higher than that of nocturnal species
which lie in wait for their prey, despite their obvious
thermophilia. This underlines the importance of
knowing, in studies of comparative thermoregulation,
not only the PBT, which is readily determined in a
temperature gradient in the laboratory, but also the
actual body temperatures to which the animals are
exposed in the field.

Acknowledgements . — This work was supported by Grant No.
071/17826 from the Australian Research Grants Committee
(SDB) and by a research grant from the University of West-
ern Australia. Travel funds for HSG were provided by the
Departement des Affaires Culturelles du Gouvernement
Frangais.

References

Bradshaw, S. D. and Main, A. R. (1968). — Behavioural
attitudes and regulation of temperature in
Amphiboliiriis lizards. /. ZooL, 154: 193-221.

Brattstrom, B. H. (1965). — Body temperatures of reptiles.
Am. Midi. Nat., 73: 376-442.

Bui Ai, Olivier, H. Ambid, L. and Saint Girons, H. (1975). — •
Enregistrement continu par biotelemetrie de la
temperature interne de Reptiles et de Mammiferes
hibernants de petite taille. C. R. Acad. Sc.
Paris, 280; 1015-1018.

Cowles, R. B. and Bogert, C. M. (1944). — A preliminary study
of the thermal requirements of desert reptiles.
Bull. Amer. Mus. Nat. Hist., 83: 261-296.

Gehrmann, W. H. (1971). — Influence of constant illumination
on thermal preference in the immature water
snake, Natrix erytrogaster transversa. Physiol.
ZooL, 44: 84-89.

Heath, J. E. (1964). — Reptilian thermoregulation; evaluation
of field studies. Science, 146: 784-785.

Heatwole, H. (1976). — Reptile Ecology. University of

Queensland Press, St. Lucia.

Jacobson, E. R. and Whitford. W. C. (1971). — Physiological
responses to temperature in the patch-nosed
snake, Salvadora exalepis. Herpetologica, 27:
289-295.

Johnson, C. R. (1972). — Thermoregulation in pythons. I. Effect
of shelter, substrate type and posture on body
temperature of the Australian carpet python,
Morelia spilotes rariegata. Comp. Biochem.
Physiol, 43: 271-278.

Kitchell, J. F. (1969). — Thermophilic and thermophobic re-
sponses of snakes in a thermal gradient. Copeia
(1969): 189-191.

Licht, P., Dawson, W. R., Shoemaker, V. H. and Main,
A. R. (1966). — Observations on the thermal rela-
tions of Western Australian lizards. Copeia
(1966): 97-110.

McGinnis, S. M. and Moore, R. G. (1969). — Thermoregula-
tion in the boa constrictor. Boa constrictor.
Herpetologica, 25: 38-45.

Naulleau, G. and Marques, M. (1973). — Etude bioteleme-
trique preliminaire de la thermoregulation de la
digestion chez Vipera aspis. C. R. Acad. Sc.
Paris, 276: 3433-3436.

Osgood, D. W. (1970). — Thermoregulation in water snakes
studied by telemetry. Copeia (1970): 560-570.

Ruibal, R. and Philibosian, R. (1970). — Eurythermy and niche
expansion in lizards. Copeia (1970): 645-653.

Saint Girons, H. (1975). — Observations preliminaires sur la
thermoregulation des Viperes d’Europe. Vie
Milieu, C 25: 137-168.

Saint Girons, H. (1978). — Thermoregulation compar^e des
Viperes d’Europe. Etudes biotelemetriques.

Terre Vie, 32: 417-440.

Saint Girons, H. and Saint Girons, M. C. (1956). — Cycle

d’activite et thermoregulation chez les Reptiles

(Lezards et Serpents). Vie Milieu, 7: 133-226.

Shine, R. (1976). — Ecological studies on Australian elapid

snakes (Ophidia, Elapidae). Unpublished thesis.
University of New England, Armidale, Australia,
254 p.

Spellerberg, I. F. and Phelps, T. E. (1975). — Voluntary tem-
perature of the snake, Coronella austriaca.
Copeia (1975): 183-185.

Stewart, G. R. (1965). — Thermal ecology of the garter snakes
Thamnophis sirtalis concinnus (Hallowell) and
Thamnophis ordinoides (Baird and Girard).
Herpetologica, 21; 81-102.

Templeton. J. R. (1970). — Reptiles, in Whitthow, G. C. (ed.),
Comparative Physiology of Thermoregulation,
Vol. T, Academic Press, New York, p. 167-221.

Webb, G. (1973). — Some aspects of thermal gradients in
Reptiles. Unpublished Ph.D. thesis. University
of New England, Armidale, Australia.

Werner, Y. L. and Whitaker, A. H. (1978). — Observations
and comments on the body temperatures of some
New Zealand reptiles. New Zealand J. ZooL,
5: 375-393.

Witten, G. J. (1969). — Aspects of the distribution and pre-
ferred temperatures of the suborder Serpentes
in north-eastern New South Wales. Unpublished
Hons, thesis. University of New England, Armi-
dale, Australia.

16

Journal of the Royal Society of Western Australia, Vol. 4, Part I, 1981. pp. 17-22.

The distribution of benthic inacrollora in the Swan River estuary,

Western Australia

by Bruce M. Allender
(Communicated by A. J. McComb)

Botany Department, Monash University, Clayton, Vic., 3168

Manuscript received 27 November 1979; accepted 19 February 1980

Abstract

A survey of 53 of the most common benthic plants in the Swan River estuary shows
the total number of species and their vertical distribution becomes smaller, while the
proportion of chlorophycean species becomes larger, upstream from the mouth. Rapid and
thorough freshwater flushing of the estuary in winter (June-August) results in a considerable
decrease in species numbers and the survival of a few tolerant species, with rapid
recolonization of the estuary when saline conditions return. The large number of algal
species present suggests that pollution effects are low.

Introduction

In contrast with the estuaries of Europe and
North America, the benthic macroflora of Austra-
lian estuaries has received very little ecological atten-
tion (Bayly 1975, Ducker, Brown and Calder 1977).
In the case of the Sw'an River estuary, only brief
species lists are provided by Thompson (1946) and
Royce (1955). The recent book by Riggert (1978)
provides an excellent account of the natural history
of the Swan River estuary and contains a brief
descriptive overview of the benthic flora.

This study provides data on seasonal, horizontal
and vertical distribution of the macroflora as a base-
line for future studies of changes in the flora of the
Swan River estuary. The distribution of the Swan
River estuary flora is compared with that of northern
hemisphere estuaries, especially with a view to using
the benthic plants as indices of pollution and other
environmental disturbances.

Methods

The species of benthic multicellular plants of the
estuary (including the diatom Melosira moniliformis)
were collected as scrapings from all substrates (in-
cluding sand, rock, wood, debris, shell fish) from
the shoreline out to the limits of the photic zone at
ten sites (Fig. 1) at 3-weekly intervals during 1968.
The upper and lower depth limits of the plants were
recorded, together with surface water temperatures
(mercury thermometer) and salinities (conductivity
meter). Tide level data were obtained from the
Western Australian Public Works Department tide
gauge near station 7 (Fig. 1), and from the Fre-
mantle Port Authority gauge at the mouth of the
estuary.

The upper limit of the study area was arbitrarily
set at the junction of the Swan and Helena Rivers
where the salinity was no greater than 5‘Voo and

Figure 1 . Map of the Swan River estuary showing sampling stations.

beyond which only 1-2 species of benthic algae
occurred. The distribution of macroflora in the Can-
ning River (stations 7A and 8A) was similar to that
of the major arm of the estuary and will not be
considered here.

Results

Hydrology

The hydrology of the Swan River estuary has been
fully documented by Rochford (1951) and Spencer
(1956). The seasonal phases of temperature and
salinity were monitored during the study period to
allow correlations with the distribution of the benthic
flora. The summer-autumn phase was marine-
dominated upstream to station 7 (Fig. 2), with
salinity decreasing and water temperature increasing
further upstream. After winter rainfall and fresh-

17

Journal of the Royal Society of Western Australia, Vol. 4, Part !. 1981.

Figure 2. -- Water temperature and salinity isopleths of the Swan
River estuary. The stations are from Figure 1 and are scaled in
distance upstream from the estuary mouth. A. -surface isotherms
(°C), B. — surface isohalines (Voo)-

water runoff, the winter-spring phase had a halocline
with cool freshwater to 2-5 m depth and high tur-
bidity throughout the estuary. The tidal amplitude
of about 0.9 m at the estuary mouth gradually de-
creased upstream. The average high tide level during
December and January (summer) was 0.3-0. 4 m lower

than during June and July (winter) because of the
lower mean sea level and considerably reduced river
flow in summer.

Benthic Flora

Sixty-nine benthic species were identified in the
Swan River estuary, of which four were angiosperms.
The distribution of 53 of the most common species
was used for the ecological analysis. The species of
Enteromorpha, Cladophora and several Cyanophyta
have not been reliably determined, and this is a
world-wide problem (apart from some regional
studies). These species, of which there are probably
2-4 per genus, are grouped under the generic name.
A preliminary species list is provided in the Appen-
dix and voucher specimens are deposited at the
University of Western Australia.

The maximum (usually summer) horizontal dis-
tributions of the species are shown in Table 3.
The proportions of Phaeophyta and Rhodophyta to
Chlorophyta species became smaller with increasing
distance from the mouth of the estuary. The re-
duction in the total number of species upstream was
highly correlated with surface salinity conditions
(Table 1). During the late winter freshwater months,
few species occurred throughout the estuary. The
seasonal distributions of algae in the estuary (for
example stations 1-3, Table 4) show that most
species were annuals and that the time of reappear-
ance of each species varied. The proportion of
perennial to annual species increased upstream, and
the same perennial species occurred throughout the
estuary. The vertical distribution limits of the at-
tached macroalgae decreased upstream (Table 2).
The total vertical range was least in winter (July)
with both the upper and lower vertical limits gener-
ally higher than in summer (January). Most species
occurred on solid substrates (rock, wood, concrete),
and many were also epiphytic. Eight species (Table
3) were found free-floating as well as attached.
Gracilaria verrucosa, in particular, often occurred
unattached and deeper than other attached algae.

Discussion

The overall distributional features of the macro-
flora of the Swan River estuary are in general agree-
ment with previous northern hemisphere studies

Table 1

The number of benthic plant species in the Swan River estuary throughout the year, correlated with the salinity distribution for each month. The

stations are shown in Figure J.

Stations Months

J

F

M

A

M

J

J

A

S

O

N

D

10 1

1

2

1

4

2

3

0

1

3

2

1

9 2

1

4

5

3

4

2

0

2

2

3

I

8 . 4

3

4

5

6

3

2

5

2

4

5

4

7 9

6

9

10

8

5

5

6

7

8

6

5

6 ... 7

7

1 1

6

9

6

5

9

5

5

8

8

5 9

10

15

15

10

14

10

1 1

7

1 1

7

7

4 11

4

8

10

10

9

9

6

4

8

8

8

3 . 17

19

21

21

18

14

17

1 1

12

13

14

13

2 13

1 1

20

21

18

15

14

1 1

9

9

13

12

1 . 16

18

24

24

20

22

24

10

9

10

17

15

r 0-87

0 70

0-76

0-73

0-81

0-94

0-88

0-39

0 63

0-82

0 84

0-87

18

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Table 2

The upper and lower vertical limits of macroalgae throughout the Swan River estuary in January {summer) and July (winter). Figures are in cm,
relative to mean sea level at Fremantle, Western Australia. The station numbers are shown in Figure 1.

Stations

1

2

3

4

5

6 !

7

8

9

10

upper limit

! 67

■! 70

i 61

T 58

1 67

-t-73

i 61

4-40 1

1-67 1

4 67

January

lower limit

-198

-46

-335

-61

-76

4 27

-15

+ 15 '

-1-18

43

upper limit

July

lower limit ...

MOI

4 91

-t 98

■ 79

+ 76

f 73

i 94

4 70

-64

, 70

-259

+ 12

-198

-15

-70

-i 46

i 9

4 64

4-52

+ 64

Table 3

The maximum horizontal distribution of 53 selected benthic plants in the Swan River estuary, independent oj the time oj the year. The stations
are shown in Figure 1. (* *) denotes species occurring bot'x free floating and attached.

Stations

Species 0123456789 10

Calothrix Crustacea ....
Rhizoclonium hookeri

Bryopsis plumosa

Porphyra lucasii
Champia parvula

Laurencia sp

Chondria dasyphyllal
Spyridia filamentosa
Melobesia membranacea
Spirulina subtilissima
Acetabularia calyculus
Sphacelaria tribuloides
Hypnea cervicornis . ..
Codium harveyi
Cladophoropsis herpestica
Oscillatoria spp.

Dictyota dichotoma ....
Calpomenia peregrina
Bangia fuscopurpurea
Gelidium pusillum
Cystoseira trinodis .. .
Hormophysa triquetra
Grateloupia filicina ....
Monospora australis
Chaetomorpha area ....
*Chaetomorpha linum
Ulva lactuca ....

Sphacelaria furcigera
Chondria tenuissima

Chondria sp

*Ceramium cliftonianum
Rosenvingea orientalis
Giffbrdia irregularis ....
Goniotrichum alsidii
Ulothrix subflaccida
Callithamnion pusillum ?
Microcoleus acutissimus
Polysiphonia subtilissima
Giffordia mitchellae ....
Calothrix spp.

Cladophora spp

Audouinella thuretii ....
Vivaria oxysperma ....

*Enteromorpha spp

*Ectocarpus siliculosus
*Gracilaria verrucosa
* Rhizoclonium riparium
*Melosira moniliformis
*Vaucheria sp.

Lyngbya lutea
Zostera mucronata ....
Halophila ovalis
Potaniogeton pectinatus

19

Journal of ihe Royal Society of Western Australia. Vol. 4. Part I. 1981.

Table 4

The seasonal distribution of benthic plants in the lower Swan River enuary {stations 1-3 in Figure /)-

Species

Months

J F M A M J JASON

D

Codium harveyi
Vaucheria sp.

Lyngbya lutea
SpiruHna subiilissima
Chondria sp.

\ticrocoleus actissimus
Vivaria oxysperma
Porphyra lucasii
Cladophoropsis herpestica
\felobesia membranacea
Bangia fuscopurpurea
Bryopsis plumosa
Spvridia filamentosa
CalothrLx spp.
Goniotrichum alsidii
Ceramium cliftonianum
Chondria tenuissima
Laurencia sp.

L'lorhrix subftaccida
Rosenvingea orientalis
Cystoseira trinodis
Hypnea cervicornis
OsciUatoria spp.

Giffordia spp.

Champia parvula?
Sfonospora australis
Dicryota dichotoma
Polysiphonia subtilissima
Sphacelaria spp.
Colpomenia peregrina
Chaetomorpha spp.
\felosira moniliformis
Callithamnion pusillum?
L'lva lactuca
Grateloupia filicina
Enteromorpha spp.
Rhizoclonium riparium
Gelidium pusillum
Gracilaria verrucosa
Ectocarpus siliculosus
Audouinella tkuretii
Cladophora spp.

Halophila ovalis

(e.g. Conover 1958. den Hartog 1967. Mathieson and
Fralick 1972, 1973. Kjeldsen and Phinney 1971), in
that there are fewer and fewer species of essentially
marine algae penetrating upstream from the estuar>‘
mouth. A causal relationship between species pre-
sence and salinity distribution in estuarine environ-
ments is supported by experimental evidence for the
deleterious effects of freshwater upon the growth
and metabolism of macroalgae (e.g. Gessner and
Schramm 1971. Kjeldsen and Phinney 1971).

The marked two-phase hydrology of the Swan
River estuary is reflected in the sudden winter de-
crease in the number of algal species and their popu-
lations in the estuary, an effect attributed to the
rapid flushing of the estuary with cool, turbid fresh-
water from the Swan. Helena and Canning Rivers.
Although a halocline persists through winter with
saline water at depths greater than 2-5 m almost
all the benthic flora is shallow water and within
the freshwater zone (Table 2).

The seasonal reduction in species diversity in the
Swan River estuarv' is not a feature of the nonhem
hemisphere estuaries mentioned above. Consequently,
the flora of the Swan River estuary may be cate-
gorized into either annual or perennial groups de-
pending upon whether the plants survive the winter
season. However some species 'e.g. Enteromorpha

spp. and Cladophora spp.) do not conveniently fit
into either category as they are continuously repre-
sented by successive generations 'the seasonal annual
concept of Sears and Wilce 1975). There is the
additional consideration of physiological races of
species adapted to different conditions within the
same estuary 'Bolton I977». These mechanisms of
rapid population turnover and adaptation must in-
crease the tolerance and distributional limits of some
estuarine species. Most annual and perennial species
repopulate rapidly with the return of saline condi-
tions in summer. However variations in times of
reappearance of the annual species suggests that
there are differences in physiology or over-wintering
strategy. For example, regrowth from persistent frag-
ments may be faster than growth from spores.

The vertical distribution of estuarine algae has
received little attention apart from that observed
in the intertidal zone 'den Hartog 1967) and in
brackish water submergence in fjords < Gessner and
Schramm 1971). In the Swan River estuary the
reduced vertical ranges of attached macroalgae up-
stream and during the freshwater phase (Table 2)
may be because the deep water species (e.g. \Iono-
spora australis, Gelidium pusillum and Polysiphonia
subtilissima/ cannot tolerate continuous exposure to
low salinities, although increased turbidity in winter
also may be involved.

20

Journal of the Royal Society of Western Australia. Vol. 4, Part 1, 1981.

The number of benthic species in estuaries ap-
parently depends upon the penetration and duration
of marine water in the estuaries. Estuaries with more
than 70 algal species, for example Great Pond,
Massachusetts (Conover 1958) and Great Bay, New
Hampshire (Mathieson and Fralick 1972)
are strongly marine influenced for most of
the year. The Swan River estuary is probably in
this category despite the severe freshwater influence
of winter. Estuaries with a large freshwater influence
or those affected by pollution contain fewer (about
30) species (Edwards 1972, Mathieson and Fralick
1973). With at least 65 species of benthic algae in
the Swan River estuary, the system shows no evidence
of pollution effects.

Acknowledgements. — This study was done at the Botany
Department, University of Western Australia; the assistance
and guidance of Mr. G. G. Smith are gratefully appreciated.
Dr. A. C. Mathieson advised during preparation of the
manuscript.

References

Baldock, R. N. (1976).— The Griffithsieae group of the
Ceramiaceae (Rhodophyta) and its Southern
Australian representatives. Aust J. Bot., 24:
509-593.

Bayly, I. A. E. (1975). — Australian Estuaries. Proc. Ecol.
Soc. Aiist., 8: 41-66.

Bolton, J. J. (1977). — Physiological salinity races in estuarine
benthic algae. J. PliycoL, 13 (Supp.): 7.

Sliding, C. (1957). — Studies in Rhizoclonium 1. Life history
of two species. Bot. Not., 110: 271-275.

Sliding, C. (1963).— A critical survey of European taxa in the
Ulvales. Part 1. Capsosiphon, Percursaria,

Blidingia, Enteromorpha. Opera Bot., 8: 1-160.
Sliding, C. (1968). — A critical survey of European taxa in the
Ulvales. Part II. Viva, Vivaria, Monostroma,
Kornmannia. Bot. Not., 121: 534-629
Chapman, V. J. (1956). — The marine algae of New Zealand.

Part 1. Myxophyceae and Chlorophyceae. J.
Linn. Soc. Lond. (Bot.), 55; 333-501.

Chapman, V. J. (1969). — The Marine Algae of New Zealand.

Part III: Rhodophyceae Issue 1. J. Cramer.

Lehre., 113p.

Clayton, M. N. (1974). — Studies on the development, life
history and taxonomy of the Ectocarpales
(Phaeophyta) in Southern Australia. Aust. J.
Bot.„ 22: 743-813.

Clayton, M. N. (1975). — A study of variation in Australian
species of Colpomenia (Phaeophyta, Scytosi-
phonales). Phycologia, 14: 187-195.

Conover, J. T. (1958). — Seasonal growth of benthic marine
plants as related to environmental factors in an
estuary. Pub. Inst. Mar. Sci. Vniv. Texas, 5;
97-147.

Cribb, A. B. (1958). — Records of marine algae from south-
eastern Queensland. IV. Caiilerpa. Vniv. Qld.
Pap. Dept. Bot., 3: 193-220.

Cribb, A. B. (I960). — Records of marine algae from south-
eastern Queensland. V. Vniv. Qld. Pap. Dept Bot.,
4: 3-31.

Cupp, E. E. (1943). — Marine Plankton Diatoms of the West
Coast of North America. University Microfilms,
Michigan. 237p.

Dawson, E. Y. (1960). — Marine red algae of Pacific Mexico.

Part 3. Cryptonemiales, Corallinaceae subf
Melobesioideae. Pac. Nat., 2: 3-125.
Desikachary, T. V. (1959). — Cyanophyta. Academic Press,
New York, 686p.

Ducker, S. C., Brown, V. B. and Calder, D. M. (1977). —
An Identification of the Aquatic Vegetation in
the Gippsland Lakes. Ministry for Conservation,
Victoria. Environmental Studies Programme

nip.

Edwards, P. (1972). — Benthic algae in polluted estuaries.
Mar. Poll. Bull., 3: 55-60.

Fan, K. C. (1956). — Revision of Calothrix Ag. Rev. Alg., 3;
154-178

Gessner, F. and Schramm, W. (1971). — Salinity, in Kinne, O.

(ed.). Marine Ecology Vol. 1 Pt. 2. Wiley-
Interscience, New York. p. 705-820.

Hartog, C. den ((1967). — Brackish water as an environment
for algae. Blumea, 15: 31-43.

Hartog, C. den (1970). — The Sea-Grasses of the World.
North-Holland Pub. Co., Amsterdam, 275p.

Harvey, W. H. (1855). — Some account of the marine botany
of the colony of Western Australia. Trans. R.
Irish Acad., 22: 525-566.

Kjeldsen, C. K and Phinney, H. K. (1971).— Effects of varia-
tions of salinity and temperature on some
estuarine macro-algae. Proc. Internat. Seaweed

Symp., 7: 301-308.

Kjeldsen, C. K. and Phinney, H. K. (1973). — Estuarine macro-
algae of Yaquina Bay, Newport, Oregon.
Madrono, 22: 85-94.

Levring, T. (1953). — The marine algae of Australia. I.

Rhodophyta: Goniotrichales, Bangiales and Nema-
lionales. Arkiv. Bot. Ser. 22: 457-530.

Lindauer, V. W., Chapman V. J. and Aiken, M. (1961). —

The marine algae of New Zealand. Part II.

Phaeophyceae. Nov. Med., 3: 1-350.

Lucas, A. H. S. and Perrin, F. (1947). — The Seaweeds of
South Australia Part II. Government Printer,
Adelaide. 458p.

Mathieson, A. C. and Fralick, R. A. (1972). — Investigations
of New England marine algae V. The algal
vegetation of the Hampton-Seabrook Estuary
and the open coast near Hampton, New Hamp-
shire. Rhodora, 74: 405-435.

Mathieson, A. C. and Fralick R. A. (1973). — Benthic algae
and vascular plants of the lower Merrimack
River and adjacent shoreline. Rhodora, IS:
52-64.

May, V. (1948). — The algal genus Gracilaria in Australia.
C.S.I.R.O. Bull, 235: 1-64.

Misra, J. N. (1966). — Phaeophyceae in India. Indian Council
of Agr. Res., New Delhi, 203p.

Papenfuss, G. F. and Jensen, J. B. (1967). — The morphology,
taxonomy of Hurmophysa (Fucales: Cysto-

seiraceae). Phytomorphology, 17: 42-47.

Papenfuss, G. F. and Jensen J. B. (1967). — The morphology,
taxonomy and nomenclature of Cystophyllum
trinode (Forsskal) J. Agardh and Cystoseira
rnyrica (S. G. Gmelin) C. Agardh (Fucales:
Cystoseiraceae. Blumea 15: 17-24.

Ramanalhan, K. R. (1964). — Ulotrichales. Indian Council of
Agr. Res, New Delhi. 188p.

Reedman, D. J. and Womersley, H. B. S. (1976). — Southern
Australian species of Champia and Chylocladia
(Rhodomeniales: Rhodophyta). Trans. Roy. Soc.
South Aust., 100: 75-104.

Riggert, T. L. (1978). — The Swan River Estuary Develop-
ment, Management and Preservation. Swan
River Conservation Board, Perth, 137p.

Rochford, D. J. (1951). — Studies of Australian estuarine
hydrology I. Introduction and comparative,
features. Aust. J. Mar. Freshwater Res., 2:
1-1 17.

Royce. R. D. (1955). — Algae of the Swan River, in Swan
River Reference Committee, Report by sub-
committee on Pollution of the Swan River. Gov-
ernment Printer, Perth.

Sears, J. R. and Wilce, R. T. (1975). — Sublittoral, benthic
marine algae of southern Care Cod and
adjacent islands: Seasonal periodicity, associa-

tions, diversity and floristic composition. Ecol.
Monogr., 45: 337-365.

Silva, P. C. and Womersley, H. B. S. (1965). — The genus
Codiiim (Chlorophyta) in southern Australia.
Aust. J. Bot., 4: 261-289.

Smith, G. G. and Marchant, N. G. (1961). — A census of
aquatic plants of Western Australia. W.A. Nat.,
8: 5-11.

Soderstrom, K. M. (1963) — Studies on Cladophora. Bot. Goth.,
1: 1-147.

Solms-Laubach, H. G. (1895). — Monograph of the Acetabu-
larieae. Trans. Linn. Soc. Lond. (Bot.), 5: 1-39.

Spencer, R. S. (1956). — Studies in Australian estuarine hydro-
logy II. The Swan River. Aust. J. Mar. Fresh-
water Res., 7: 193-253.

21

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Taylor, W. R. (I960). — Marine Algae of the Eastern Tropical
and Subtropical Coasts of the Americas. Univ.
Michigan Press, Ann Arbor, 870p.

Thompson. J. M. (1945). — The fauna of the algal zone of
the Swan River Estuary. A preliminary survey
of Freshwater Bay with notes on the chief
species. J. Roy. Soc. West. Aiist., 30: 55-73.

Woelkerling, W. J. (1971), — Morphology and taxonomy of the
Aiidouinella complex (Rhodophyta) in Southern
Australia. Aust. J. Bot. Siipp. 1, 91p.

Womersley, H. B. S. (1956). — A critical survey of the marine
algae of Southern Australia I. Chlorophyta.

Aust. J. Mar. Freshwater Res., 7: 343-383.

Wcmersley, H. B. S. (1978) — Southern Australian species of
Ceramium Roth (Rhodophyta), Aust. J. Mar.
Freshwater Res., 29: 205-257,

Womersley, H. B. S. (1979). — Southern Australian species of
Polysiphonia. Aust. J. Bot, 27: 459-528.

Womersley, H. B. S. and Carlledge, S. A. (1975). — The

Southern Australian species of Spyridia (Cera-

miaceae: Rhodophyta). Trans. Roy. Soc. South
Aust., 99: 221-233.

Womersley, H. B. S. and Conway, E. (1975). — Porphyra and
Porphyropsis (Rhodophyta) in Southern Australia.
Trans. Roy. Soc. South Aust., 99; 59-70.

Appendix

A preliminary list of benthic marine algae and sea-
grasses in the Swan River estuary. The main

reference used in identification are also given.

Cyanophyta

Calothrix ccnjervicola (Rcth) C. Agardh? Fan 1956, Chap-
man 1956.

Calothrix Crustacea Thuret Fan 1956. Chapman 1956.
Calothrix sp.

Lynfihya lutea (C. Agardh) Gomont Chapman 1956. Desi-
kachary 1959.

.\ticroco!eus acutissinws Gardner Chapman 1956. Desi-

kachary 1959.

Oscillatoria amphibia C. Agardh Desikachary 1959.
Oscillatoria sp. 1.

Oscillatoria sp. 2.

Spirulina .whtilissima Kuetzing Chapman 1956. Desikachary
1959.

Chlorophyta

Acetahuiaria calvculus Quoy et Gaimard Solms-Laubach
1895.

Bryopsis plumosa (Hudson) C. Agardh Chapman 1956,
Caulerpa racemosa (Forsskal) J. Agardh var. laetevirens
Montagne) Wever van Bosse Cribb 1958,

Chaetomorpha aerea (Dillwyn) Kuetzing Chapman 1956.
Chaetomorpha linum (Mueller) Kuetzing Chapman 1956.
Cladophora albida (Hudson) Kuetzing? Soderstrom 1963.
Cladophora fascicularis (Mertens in C. Ag.) Kuetzing?
Soderstrom 1963.

Cladophora fiexitosa (Mueller) Kuetzing? Soderstrom 1963.
Cladophora harvey Womersley? Womersley 1956.
Cladophora laetevirens (Dillwyn) Kuetzing? Soderstrom 1963.
Cladophora sp.

Cladophoropsis herpestica (Montagne) Howe Cribb 1960.

C odium harveyi Silva Silva and Womersley 1956.
Enteromorpha ahlneriana Eliding? Eliding 1963.

Enteromorpha compressa (Linnaeus) Greville Sliding 1963.
Enteromorpha fiexuosa (Wulfen ex Roth) J. Agardh? Sliding
1963.

Enteromorpha sp.

Rhizoclonium hookeri Kuetzing? Chapman 1956.

Rhizocloniiim ripariiim (Roth) Harvey Chapman 1956. Eliding
1957.

Vlothrix subfiaccida Wille Ramanathan 1964.

Ulothrix sp.

Viva lactuca Linnaeus Chapman 1956.

Vivaria o.xysperma (Kuetzing) Sliding var. o.xysperma Eliding
Eliding 1968.

Phaeophyta

Colpomenia peregrina (Savageau) Hamel Clayton 1975.
Cystoseira trinodis (Forsskal) C. Agardh Papenfuss and
Jensen 1967.

Dictyota dichotoma (Hudson) Lamouroux Lindauer Chapman
and Aiken 1961.

Ectocarpus siliculosus (Dillwyn) Lyngbye Clayton 1974.
Giffordia mitchellae (Harvey) Hamel Clayton 1974.

Giffordia irregularis (Kuetzing) Joly Clayton 1974.
Horrnophysa triquetra (C. Agardh) Kuetzing Papenfuss 1967.
Rosenvingea orientalis (J. Agardh) Boergesen Misra 1966.
Sphacelaria furcigera Kuetzing Misra 1966.

Sphacelaria tribuloides Meneghini Misra 1966.

Chrysophyta

Melosira moniliformis (Mueller) C. Agardh Cupp 1943.
Xanthophyta

Vaucheria sp.

Rhodophyta

Aiidouinella thuretii (Bornet) Woelkerling Woelkerling 1971.
Bangia fiiscopurpurea (Dillwyn) Lyngbye Levring 1953.
Callithamnion piisillum Harvey? Harvey 1855.

Ceramium cliftonianum J. Agardh Womersley 1978.

Champia parvula (C. Agardh) Harvey Reedman and Womer-
sley 1976.

Chondria dasyphylla (Woodward) C. Agardh? Harvey 1855.
Chondria tenuissima (Goodenough & Woodward) C. Agardh
Lucas and Perrin 1947.

Chondria sp,

Monospora australis (Harvey) J. Agardh Baldock 1976.
Gelidiurn pusillum (Stackhouse) Le Jolis Chapman 1969.
Goniotrichum alsidii (Zanardini) Howe Levring 1953.
Gracilaria verrucosa (Hudson) Papenfuss May 1948.
Grateloupia filicina (Wulfen) C. Agardh Lucas and Perrin
1947.

Griffithsia crassiusciila C. Agardh Baldock 1976.

Hypnea cervicornis J. Agardh Taylor 1960.

Laurencia sp.

Melobesia metnbranaceae (Esper) Lamouroux? Dawson 1960.
Polysiphonia subtilissima Montagne Womersley 1979.
Porphyra lucasii Levring Womersley and Conway 1975.
Spyridia filamentosa (Wulfen) Harvey Womersley and Cart-
ledge 1975.

Anthophyta

Halophila ovalis (R. Brown) Hooker den Hartog 1970.
Heterozostera tasmanica den Hartog den Hartog 1970,
Potamogeton pectinatiis Linnaeus Smith and Marchant 1961.
Zostera mucronata den Hartog den Hartog 1970.

22

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981, pp. 23-26.

Fish scales from the Permian of Western Australia

by N. W. Archbold

(Communicated by M. H. Johnstone)

Geology Department, University of Melbourne, Parkville, Vic. 3052.
Manuscript received 27 November 1979; accepted 18 March J980

Abstract

Fish scales are recorded for the first time from the Permian of Western Australia. The
scales, from the Byro Group in the Carnarvon Basin, are distinct from any Permian fish
scales previously described from the Gondwanaland continents. The fish may have
inhabited an open marine environment.

Introduction

Remains of fish are sporadic in the Permian de-
posits of the Gondwanaland continents. The present
note documents the recent discovery of fish scales
from the Coyrie Formation, Byro Group, of the
Carnarvon Basin, Western Australia. These fish
scales, collected during the recent mapping of the
Carnarvon Basin by the Geological Survey of West-
ern Australia (GSWA) (see Hocking et al. 1980 for
revised stratigraphic nomenclature) are noteworthy
because of their mode of occurrence, size and the
environment of deposition.

Australian Permian fish

Few fish have been recorded from the Permian
strata of Australia. The Sydney Basin (eastern
Australia) has yielded the genus Urosthenes Dana
(1848a, p.433; 1848b, p.I49; 1849, p.l7I, Atlas PI.
1 fig. 1-la) with the type species U. australis Dana
from the Newcastle Coal Measures and V . latus
Woodward (1931) from the same strata. Woodward
(1940) subsequently described a representative of
Elonichthys from the same strata. The report by
de Koninck (1877, p.354) of the bradyodont shark
Tomodus convexus Agassiz? from New South Wales
cannot be confirmed as the specimens were destroyed
by fire (Teichert 1943, p. 543-4). Urosthenes Dana
lived in a non-marine habitat whereas de Koninck’s
bradyodont shark was probably of marine origin.
Fossil fish remains have also been recorded from the
Bowen Basin of Queensland by Dunstan (1901).
The Queensland material included spines, vertebrae
and scales; however, the specimens have apparently
never been described or figured.

Records of fish in the Western Australian Permian
Basins are restricted, to date, to several reports from
the Carnarvon Basin. Helicoprion Karpinsky has
been described from the Wandagee Formation
(Woodward, 1886; Teichert, 1940) as well as rep-
resentatives of bradyodont sharks (Helodiis Agassiz
and Crassidonta Branson) from the same formation
(Teichert, 1943). The Wandagee Formation pos-
sesses a diverse invertebrate fauna, including articu-
late brachiopods, molluscs and crinoids, indicative

of an open marine environment. Helicoprion has
also been recorded from the Bulgadoo Shale (Con-
don, 1967) a formation also with a diverse marine
invertebrate fauna.

The new discovery

In addition to the fish scales, GSWA sample 44553
(Lat. 25°49'28'^ S, Long. 115°38'33"E, about 300 m
south of Wooramel River, north-east of Darcy Hill;
near top of Coyrie Formation) has yielded abun-
dant, although invariably poorly preserved, specimens
of Fusispirifer byroensis (Glauert 1912), Glauert’s
species is diagnostic of the Coyrie Formation and
the Mallens Sandstone. Three specimens of Fusi-
spirijer byroensis from sample 44553 have been
registered in the GSWA collection with the numbers
FI 1014, FI 1015, FI 1016. The age of these strati-
graphic units is well controlled and is considered to
be early Permian (Late Artinskian Stage, Early
Baigendzinian Substage, Dickins 1976).

The discovery of fish scales from the same locality
as abundant articulate brachiopods is of considerable
interest because of the indubitably marine environ-
ment of deposition. The fish scales, described below,
are large, ranging in length from 1 cm to 1.7 cm.
The scales, well over one hundred specimens, are
preserved in a single block of rock some 1 2 cm x
8 cm in size. The scales are thickly distributed, in
random orientation throughout the block, with no
indication of bedding or sedimentary structures. Such
an aggregate of scales is suggestive of coprolitic
accumulation, although no discrete coprolite shape
was observable. Breaking the block revealed further
scales throughout the entire specimen. The block
is ferruginised with some original, though decom-
posed, material of the scales remaining with the
impressions of the scales. If the block is coprolitic
its size indicates a large predatory organism.

Affinities of the scales

In an attempt to identify the scales a survey of
Permian fish occurrences of the Gondwanaland con-
tinents was made. Few described fish scales were
found to be similar, probably because of the inade-

23

Journal of the Royal Society of Western Australia, Vol. 4, Part I, 1981.

24

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

quate documentation and illustrations of many re-
ports. For the present, the nomenclature of the
scales is left open, although it appear likely that the
scales are of palaeoniscid affinity.

Permian fish scales have been recorded from
Southern Africa, South America and India. How-
ever despite the substantial records the only fish
scales from Southern Africa comparable to the
present specirnens from Western Australia, with
respect to their apparent concentric ornament and
strongly digitate hind margin, are the flank fish
scales of Acrolepis molyneuxi figured by Woodward
(1903, 1910). The South African fish scales are
much smaller than the new Western Australian
specimens.

The records of fish scales from the Late Palaeozoic
of South America are plentiful, however, descriptions
and illustrations are few. Fish scales described and
figured by Martins (1948) are closely comparable
with the new material especially in details of
ornament and the digitate hind margin. Martins’
specimens, from the Serie Marica, Rio Grande do
Sol, are, however, smaller and possess a coarser
concentric ornament than the Western Australian
scales. Associated with the fish scales, Martins re-
corded an impoverished marine fauna of inarticulate
brachiopods \ Lingula and Orbiculoidea) indicative
of marginal marine deposits.

Environment of the Western Australian scales

The determination of the environment of deposi-
tion of fossil fish is of critical importance and
requires careful examination of stratigraphic evidence.
Romer (1971, p.l20) has commented on the un-
certainty of habitat of many of the described forms,
and on the problem of euryhaline species as well as
those species with differences between early and
late life stages. As noted above the Western
Australian scales occur in sediments deposited in
an open marine environment. Nevertheless caution
about the habitat of the Western Australian fish is
advisable, because of the inferred coprolite source
of the specimens.

Systematic Palaeontology

Class PISCES

Incertae Sedis.

Description: The scales (Fig. 1) are of varying
shape and outline, reflecting the varying position of
the scales on the body of the fish. Length of the
scales varies from 1 cm to 1.7 cm. The hind margin
of the scales is digitate in an anastomosing pattern.
The digitate portion of the scale is up to one
quarter of the total length of the scale. The scales
are thick (up to 0.5 mm) with one surface being
smooth (the inner surface?), while the other surface
possesses an ornament of sub-concentric lines and
a micro-ornament of striae which increase in
number anteriorly by intercalation. On worn im-
pressions of scales this micro-ornament is lost.

Discussion: The thickness of the scales and the
micro-ornament make these scales distinct from any
record elsewhere from the Permian. The scales de-
scribed by Martins (1948) discussed above are
impressions that are possibly too worn (or the
lithology may be too coarse) to preserve any micro-
ornament. Close comparison was indicated with
scales figured by Martins; however, as these were
left in open nomenclature little can be added except
that both the South American and Western Australian
forms are distinct and possibly represent at least
one new genus likely to be of palaeoniscid affinity.

Acknowledgements. — I thank the Director of the Geological
Survey of Western Australia and the curator of collections.
Dr. A. E. Cockbain, for providing material from the collections
in their care. Dr. A. E. Cockbain provided information on
the stratigraphy and locality of the specimens. Dr. G. A.
Thomas, University of Melbourne, criticallv read the manu-
script. The assistance of the staff of the Baillieu Library is
gratefully acknowledged and Mrs. G. Waterman typed the
manuscript. The work was carried out while 1 was in receipt
of a University of Melbourne Postgraduate Award.

References

Condon, M. A. (1967). — The Geology of the Carnarvon Basin,
Western Australia. Part 2: Permian Stratigraphy.
Bull. Bur. Miner. Resonr. Geol. Geophysics. Aust.,
77: 1-191.

Dana, J. D. (1848a). — Fossils of the Exploring Expedition
under the command of Charles Wilkes, U.S.N.:
a fossil fish from Australia, and a Belemnite
from Tierra del Fuego. Am. J. Sci. Ser. 2,
5: 433-435.

Dana, J. D. (1848b). — Fossils of the exploring expedition
under the command of Charles Wilkes, U.S.N.: a
fossil fish from Australia and a Belemnite from
Tierra del Fuego. Ann. Mag. not. Hist. Ser. 2,
2: 149-150.

Dana. J. D. (1849. — Fossils of New South Wales, in, United
States exploring expedition. During the years
J838, 1839, 1840, 1841, 1842 under the command
of Charles Wilkes, U.S.N. Vol. 10. Geology. Ap-
pendix 1(1): 681-720. Philadelphia. C. Sherman.

Dickins, J. M. (1976). — Correlation chart for the Permian
System of Australia. Bull. Bur. Miner. Resour.
Geol. Geophys. Aust., 156: 1-26.

Dunston, B. (1901). — Notes on fossil fish at Duaringa, Central
Railway Line. Ann. Rep. Under Secretary Mines,
1900: 192-193.

Glauert, L. (1912). — Permo-Carboniferous fossils from Byro
Station. Murchison District. Rec. West. Aust.
Mus., 1; 75-77.

Hocking, R. M., Moore, P. S. and Moors, H. T. (1980). —
Modified stratigraphic nomenclature and con-
cepts in the Palaeozoic sequence of the Carnarvon
Basin, W.A. West. Aust. Geol. Sitrv. Ann.
Rept. 1979, p. 51-55.

Koninck, L. G. de (1877). — Recherches sur less fossiles
Paleozoiques de la Nouvelle-Galles du Sud
(Australie). Mon. Soc. Sci. nat Liege. Ser. 2
7: 1-235.

Martins, E. A. (1948). — Fosseis marinhos na Serie Marica. Rio
Grande do sol. Mineraceo Metahirgia 12(71);
237-239.

Romer, A. S. (1971). — Tetrapod vertebrates and Gondwana-
land. Proc., papers Second Gondwana Syposium.
p. 111-124. C.S.I.R. Scientia. Pretoria.

Figure 1. Fish scales from GSWA sample 44553. All specimens whitened with ammonium chloride A
fish scale x 5. B.— GSWA FI 1007 fish scale x 5. C— GSWA FI 1008 fish scale x 5 D— GSWA '
E.— GSWA FllOlO fish scale x 5. F.— GSWA FllOll fish scale x 5. G.— GSWA F11016
with fish scales x 1, H. — GSWA FI 1012 portion of fish scale x 12. 1. — GSWA FI 1012 fish scale x 5.

—GSWA FI 1006
FI 1009 fish scale
portion of block

25

Teichert, C.
Teichert, C.
Woodward,

Woodward,

Journal of the Royal Society of Western Australia. Vol. 4, Part 1. 1981.

(1940). — Helicoprion in the Permian of Western
Australia. J. Paleont., 14: 140-149.

(1943). — Bradyodont sharks in the Permian of
Western Australia. Am. J. Sci., 241: 543-552.

A. S. (1903). — On a new species of Acrolepis
obtained by Mr. Molyneux from the Sengwe Coal-
field. Q. Jl. Geol. Soc. Lond., 59: 285-286.

A. S. (1910). — Note on palaeoniscid fish scales
from the Ecca Shales near Ladysmith. Ann.
Natal Mus., 2: 229-231.

Woodward, A. S. (1931). — On Vrosthenes, a fossil fish from
the Upper Coal Measures of Lithgow, New
South Wales. Ann. Mag. Nat. Hist. Ser. 10,

8: 365-367.

Woodward, A. S. (1940). — A palaeoniscid fish Elonichthys
davidi) from the Newcastle coal Measures, New
South Wales. Ann. Mag. Nat. Hist. Ser, 11,

6: 462-464.

Woodward, H. (1886). — On a remarkable Ichthyodorulite
from the Carboniferous Series, Gascoyne, West-
ern Australia. Geol. Mag. Ser. 3, 3: 1-7.

26

Journal of the Royal Society of Western Australia, Vol. 4, Part I, 1981, pp. 27-32.

Observations on the breeding biology and behaviour of the long-necked tortoise,

Chelodina oblonga

by B. T. Clay

Zoology Department, University of Western Australia, Nedlands, W.A. 6009.

Manuscript received 18 March 1980; accepted 19 August 1980

Abstract

Chelodina oblonga, a common tortoise in the fresh waters of the south-western coastal
belt of Western Australia, has two nesting periods: one in spring (September to November),
and one in summer (December to January), Cool conditions with rain occur during the
spring period, and hot dry conditions prevail during the summer period. Specific weather
conditions were associated with the nesting periods including the occurrence of seasonal
rain-bearing low pressure systems, a falling barometric pressure, and an air ternperature
above 17 °C. Distances travelled by the gravid female to the nesting site were variable and
were generally greater during the spring period. Animals were active within a body
temperature of 18"C to 3TC and dehydrated quickly with air temperatures in excess of
25 °C. Difference in clutch sizes were apparent between nesting periods, and egg weights, egg
sizes and clutch sizes varied between individuals. The incubation period was almost identical
for each nesting period, ranging from 210 days to 222 days. Hatchlings from both nesting
periods emerged at the same time in mid-August.

Introduction

The family Chelidae is represented in Western
Australia by six species of fresh-water tortoise.
Chelodina rugosa is found only in the Kimberley and
C. steindachneri is found in the arid zone within the
river systems from the Irwin River south of Gerald-
ton to the De Grey River in the Pilbara. The
short-necked tortoises are represented by Emydura
australis and Elseya dentata in the Kimberley, and
Pseudemydura umbrina which occupies an area of
a few square kilometres just north-east of Perth.
The common long-necked tortoise, Chelodina ob-
longa, is found in the south-west of Western Australia
(Cogger 1975).

Although C. oblonga is common in the south-west
of Western Australia there is little literature avail-
able concerning its behaviour in the field. Burbidge
(1967) investigated the biology of Pseudemydura
umbrina and Chelodina oblonga. Nicholson (1974
pers. comm.) described the nesting behaviour of
C. oblonga.

The aim of this paper is to report on the move-
ments and breeding behaviour of a wild population
of C. oblonga. Over a period of four years climatic
and seasonal factors which are associated with
movement and reproductive biology have been
measured and an attempt was made to assess those
environmental variables which affect breeding.

Study area

Thompson Lake Nature Reserve No. 15556, vested
in the Western Australian Wildlife Authority and
managed by the Department of Fisheries & Wildlife,
and the Marsupial Breeding Station, No. 29241

Figure 1. — Map showing study areas and boundary between
the Bassendean-Spearwood Sands; scale: 1:25 000.

27

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

managed by the University of Western Australia
and vested in the Minister for Fisheries and Wildlife
are both situated in the City of Cockburn. These
study areas lie approximately 25 km south of Perth,
Western Australia at latitude 32° 10' S, longitude
115° 50' E. The total area of Thompson Lake
Reserve is 509 ha with the lake occupying 172 ha.
The area of the Marsupial Breeding Station is
253.7 ha with Banganup Lake occupying 32 ha
(Fig. 1).

The two reserves lie mostly within the Bassendean
Sand complex with the Spearwood Sands bordering
Thompson and Banganup Lakes on their west side
(Seddon 1972). The boundary between the two sands
is shown in Figure 1.

The vegetation of the higher well-drained Bassen-
dean Sands consists mainly of Jarrah (Eucalyptus
margiuaia) and Banksia spp. The vegetation on the
higher Spearwood Sands consists mainly of Banksia
spp, Jarrah and Tuart (Eucalyptus gomphocephala) .
The lower areas close to the lakes are dominated
by the Swamp Gum (E. ruclis), paperbarks
(Melaleuca spp.) and the jointed rush Bawnea
articulata in varied associations with other reeds and
rushes.

Methods and materials

Capture

Animals moving to nest were captured on the
boundary fence surrounding the Marsupial Breeding
Station. Females in the Thompson Lake Reserve
were captured as they moved to nest and other
females were followed to the nest site. Animals
were also captured in simple wire mesh fish type
traps using liver as bait.

Marking and measurement

Where possible adults were weighed on a Salter
spring balance, weighing to the nearest gm. Cara-
pace and plastron widths and lengths, body depths
and tail lengths were measured, the last from the
tip of the tail to the middle of the concave section
of the plastron with linear calipers. Stainless steel
tags were inserted in two holes drilled on the edge
at the rear of the carapace. Because the metal tag
disintegrates, the same number was also branded
on the middle of the plastron using a cauterizer.
The presence of eggs was determined by pushing
the index finger against the abdominal cavity.

Distances from the water’s edge to the nest site
were measured during the two nesting periods. Nest
sites were located by regular and systematic searching
of the study areas. Some nest sites were left un-
disturbed, marked with a wooden stake and labelled.
Each nest site was surrounded with wire mesh and
fly wire attached to the lower half to prevent
hatchlings from escaping. Other nest sites were
excavated and measured, and the eggs removed for
ether experiments. Eggs were measured with linear
calipers and weighed on a Mettler P 1200 balance.

Artificial nest sites similar to the original sites
were selected and egg chambers dug by hand. Times
from nesting to the emergence were recorded. Other
eggs were placed in glass-fronted nest chambers to
observe hatching and emergence dates.

Body, water and nest temperatures were recorded
with a YSl model 44 telethermometer.

Weather

Rainfall figures were monitored daily at the
Marsupial Breeding Station throughout the study
period. High and low pressure systems were followed
by studying the daily weather charts published by
the Western Australian Bureau of Meteorology.
Temperature and relative humidity were recorded
continuously on a Thiess hygrothermograph main-
tained in a Stevenson Screen.

Results

Mating

Although intensive observations were made daily
throughout the nesting periods, C. oblonga were
never observed copulating on land or in the water.

Sex determination

Gravid females were easily sexed. Post mortems
were carried out to determine the sex of non-gravid
females and suspected males and from these data
all tortoises were sexed from the ratio of the tail
length to the body depth. Females have a ratio of
less than 1.0 : I and the males a ratio greater
than 1.4 : 1 (Fig. 2). The difference between
females and males is highly significant (p<.001).

90 r

■ I I t - 1 i ■ . I

50 60 70 80

BODY DEPTH (mm)

Figure 2. — Ratio of tail length to body depth of male and
female Chelodina oblonga is highly significant
{.01<P<.G0D.

Nesting periods

Weather. — In south-western Australia the highest
rainfall occurs during the winter months (Western
Australian Year Book 1973). From observations
during this study tortoises moved to nest for the
laying of the first clutch of eggs at the end of

28

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

winter. The earliest movement was recorded on 9
September 1974 and the latest movement was re-
corded at the beginning of November 1976. The
second nesting period did not correlate with any
observed weather pattern.

Stimulus for movement. — During this study the lowest
recorded body temperature was 18®C with an air
temperature of 16.2°C at the time of capture. The
highest recorded body temperature was 31.0""’C with
an air temperature of 27.0°C at time of capture
(Fig. 3). Once the maximum daily temperature
remains above 17.5°C the females move to nest
(Fig. 4). Mean daily maximum temperature on days
of movement during the summer period are higher
than those during the spring period (Table 1).

32 -

30-

o

o

28

Lij 26

cr

Z5

5

£24

CL

LJ

22

20

18 - •

16 -

16

• t •

« 4— t t « I I «■■■»-«

18 20 22 24 26 28 30

AIR TEMPERATURE (°C)

SPRING I I SUMMER i

NESTING 1 I NESTING I

Figure 3. — Body and air temperatures at time of capture
of gravid females moving to nest during the spring and
summer nesting periods.

Weather patterns during the spring period charac-
teristically approach from the south-west, and associ-
ated low pressure systems are normally rain-bearing
depressions. Records during this study indicate that
the females move to nest as the barometric pressure
decreases (Fig. 5). A strong relationship between
animal movement and the approach of a rain-bearing
depression is evident. Barometric patterns typical of
those correlated with movements of females are
shown in Figure 5. Once the spring nesting period
has commenced, future spring nesting periods may
be predicted by observation of the weather patterns.
There is no relationship between the weather pattern
and the movement of the second nesting.

Movement. — During this study most animals cap-
tured were females moving to nest. The 1975/1976
data show that of the 76 animals captured, 67 were
females and 9 were males. Of the 67 females

40

30

20

Figure 4. — Females moving to nest after daily maximum
temperatures remain above 17.5°C and showing numbers
with daily maximum temperatures.

Table 1

Mean doily maximum temperature (°C) recorded on day of movement

Movement

Mean daily
maximum
temperature on
day of movement

Number of days
on which
movements
were observed

Sept. /Nov.

1973

240

7

1974

23-5

13

1975

20-6

11

Dec. /Jan.

1973/74

32 1

11

1974/75

25-9

3

1975/76

26-7

6

captured 12 animals were without eggs and it was
presumed that these had already lafd eggs (Table
2). It is evident that females move to nest during
both September/November and December/January.
Males appear to move both prior to and after the
main nesting periods (Table 2).

There was no evidence to show that females
migrate except where the natural environment is
drying up. Females during this study appeared to
move only to nest. Males captured appeared to be
migrating from one lake to the next.

Nesting and nest site

Approach to shore. — C. oblonga approached the
shore very cautiously. Remaining in shallow water
with the head held well above the water line and

29

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Figure 5. — Isobars recorded by the Weather Bureau at 1500 h
indicating approaching cold fronts, 24 gravid females
were captured moving to nest on the 6/10/74 whereas no
animals were captured on the 24/10/75. 15 gravid females
were captured 25th-26th as the depression with falling
pressure moved over the coast.

Table 2

Male and female movement during the periods (a) 1975/1976 and
(b) 1976/1977

(a)

Date

Female

Male

Sept. 1975

0

2

Oct. 1975

62

2

Nov. 1975

3

2

Jan. 1976

2

2

Feb. 1976

0

1

*67

9

• 12 females without eggs.

(b)

Date

Female

Male

Sept. 1976

1

1

Oct. 1976

1

5

Nov. 1976

13

1

0

Dec. 1976

1

Jan. 1977

4

0

20

7

at the same time resting on the lake bed, animals
would take varying lengths of time before emerging.
At this stage they were easily disturbed and would
retreat to deeper water. As observed by Hendrickson
(1958) Chelonia mydas approaches the shore in the
same way.

Order of events during nesting. — Typical nesting be-
haviour of C. oblonga taken from field note book
dated 6 October 1974:

0945 h Proceeded to study area at Thompson Lake.
A rain-bearing low depression forecast. Air
temperature 22°C with a light south-westerly
wind and 8/10 cloud cover.

0955 h Observed female tortoise leaving the water.
During the first 40 m the tortoise did not
deviate from its original course, in a south-
westerly direction. Once it gained the pro-
tection of the vegetation it used all available
cover.

1050 h Started to move in a southerly direction.

1 1 12 h Selected nest site. The site was open and
comparatively flat with little vegetation except
for native grasses. The nest site was 98 m
from the water's edge. The tortoise began dig-
ging the nest chamber. Digging the vertical
shaft was a simple process, with the tortoise
using the rear feet alternately to scoop the soil
out and place the material to one side of the
hole. Construction of the egg chamber was
at right angles to the vertical shaft and
proved more difficult and lengthy. No voiding
of cloacal fluid was observed during the
nesting.

1 126 h Nest site completed.

1 127 h Tortoise began to lay eggs. Each egg posi-

tioned in the egg chamber using each hind
foot alternatively. Ten eggs were laid.

1 130 h Egg-laying completed, the tortoise began to
refill nest chamber by scooping soil from
edge and again using the two hind feet. Once
the vertical shaft had been filled, it began
to compact the soil by raising itself on three
legs and then letting the body fall onto the soil.
This procedure appeared to be critical, as
the tortoise spent several minutes repeating the
process.

1 140 h Refilling and compaction completed, the tor-
toise rested for several minutes. After the
rest period it replaced vegetation over the
nest site, using the hind feet. Once this pro-
cedure had been completed, the nest site was
almost unrecognisable.

1 145 h The tortoise returned to the lake.

Total time taken to travel to the nest site, dig
egg chamber, lay eggs, refill and compact soil and
return to the lake, was 1 h and 50 mins. Nesting
varied considerably with climatic and soil conditions.
Mean temperatures on day of nesting — spring 22.3 °C
(20.6°C to 24°C) and summer 28°C (25.9°C to
32.rC).

Ascent to nesting site. — Once the females were some
distance from the water’s edge they were not easily
disturbed and continued in the general direction of
the nesting site. Whenever females were handled
they would void copious amounts of fluid and return
to the lake without nesting. The females did not
deviate greatly from the direction in which they
were travelling to the nest site. Only during the
latter stages of the ascent did the female deviate
to look for a suitable nest site. All females took
advantage of any thick cover, presumably to avoid
attacks by birds.

30

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

Distance to nest site. — Distance to nest site varied
considerably between the spring and summer nesting
periods (Table 3). Moll and Legler (1971) state
that distances travelled from water by females of
Pseudemys scripta are also variable. The greatest
distance to a nest site was 105 m which was recorded
in the spring nesting period, and the shortest dis-
tance to a nest site was 20 m which was recorded
in the summer nesting period.

Table 3

Differences in distances to nest site between the spring and summer
nesting periods

I i

Sept. -Nov. j Dec.-Jan

Mean distance to nest sites | 86-56 ± 10-00 i 25-38 ± 2-41
in metres (No. of nests)* ! (27) | (80)

* p <<0-001, Student’s “t” test.

Nest site. — Female tortoises appeared to have no pre-
ference for a nest site and generally chose one that
was open and free from thick vegetation (Fig. 6).

Figure 6. — A typical profile showing distances to nest sites for
the two nesting periods.

Neotropical sliders also tend to nest in relatively
open areas (Moll and Legler 1971). Females nesting
in the summer period generally nested in heavier
soils compared with the sandy soils used during the
spring nesting period.

Clutch size, egg size and weight
The largest clutch (12 eggs) was recorded in the
spring nesting period of 1975, and the smallest
clutch (3 eggs) was recorded in the summer nesting
period of 1975/1976. Egg size and weight vary

within the clutch and between individuals (Tables
4 and 6).

Table 4

Differences in clutch sizes

between the two nesting periods

Sept. -Nov.

Dec.-Jan.

Mean clutch size (No. of
nests)*

8-20 ±1-22
(15)

4-00 ± 0-21
(10)

* p << 0-001, Student’s “t” test.

Table 5

Mean temperature (°C) of air and nests between egg-laying and hatch-
ing taken over a period o/30 weeks

Air

temperature

Nest

temperature

Significance

(*)

Minimum 14-85 ±0-67

Maximum 28-18 ±0-84

Difference 1^56 ±0-44

i 20-39 ± 0-74
27-26 ± 1-00
6-87 ± 0-44

P < -001
NS

P < -001

* Student’s “t” test for paired samples.

NS — No significant difference.

Eggs taken from the two nesting periods of
1974/1975 and 1975/1976 show very little variation
in the time of incubation. In 1974/1975, 216 to
222 days were recorded to hatching, and in 1975/
1976, the period was 210 to 220 days. The average
temperature in the egg chamber ranged from a mini-
mum of 14°C. to a maximum of 29.8°C. There was a
significant difference between the average minimum
temperature of the nest and air temperatures (Table
5).

Discussion

The dark and opaque nature of the swamp water
has unfortunately precluded any direct observation
of C. oblonga copulating in the water. Burbidge
(1967) states that C. oblonga were observed copu-
lating in captivity, and that the copulatory ritual
was similar to that of Pseudemydura umbrina and
that copulation takes place in the water with the
male mounting the female from the rear, as does
Pseudemys scripta (Moll and Legler 1971). In
contrast to Chelonia mydas (the green sea turtle)
studied by Hendrickson (1958) in Sarawak, both
female and male Chelodina oblonga leave the water
and can be found on land, although the percentage
of males is well below that of the females. The
males do not appear to move during the peak
nesting periods (Table 2).

Brattstrom (1965) reports that Chelonia are
active over a much wider range of body temperatures

Table 6

Animal weights, mean egg size and clutch size of live animals

Animal weight

Carapace

Carapace

Egg weight (g)

Egg length (mm)

Egg width (mm)

Animal No.

before egg

width

length

Clutch

laying (g)

(mm)

(mm)

Max.

Min.

Mean

Max.

Min.

Mean

Max.

Min.

Mean

size

7372

1 440

224-2

134-2

11-7

11-3

11-5

36-6

35-0

35-7

23-2

22-5

22-9

8

7369

1 250

224-0

127-8

12-0

10-9

1 1 -4

36-7

35-2

32-8

23-4

22-9

23-2

12

7375

1 170

212-8

125-4

10 9

9-9

10-4

33-8

32-2

33-1

23-5

22-6

23-0

10

7378

670

113-0

113-0

6-8

5-8

6-3

31 3

30-0

30-8

18-3

18-0

18-1

6

31

Journal of the Royal Society of Western Australia, Vol. 4, Part 1, 1981.

than terrestrial lizards. Burbidge (1967) cites Lucas
(1963) in stating that Chelodina obionga has a
preferred temperature of between Ib^C and 28°C
and that from incidental observations C. obionga
is active within the range 13°C to 28°C. During
this study the body temperature ranged from 18°C
to 31°C (Fig. 3). Tolerance of air temperatures
above 25°C is minimal as the animals can only
survive a few hours due to desiccation.

Migrations have been reported in a number of
species of turtles while nesting, such as Chelonia
mydas and Lepidochelys kempi (Carr 1967), Batagur
baska (Loch 1950), Fodocnemis expansa (Roze
1964). Moll and Ledler (1971) state that migratory
behaviour has evolved where suitable nesting sites
are scarce and where feed is inadequate. Migration
could be an important factor for the survival of
the species.

During this study no females that were marked
during the spring nesting were recaptured during
the summer nesting. Professor J. M. Legler (Uni-
versity of Utah) has examined specimens of C.
obionga ovaries. Results of his investigations indicate
that double nesting could occur (Legler, pers. comm.
1976). Carr (1952) suggests that the Chelonidae and
Dermochelyidae do have multiple clutches.

It is suggested that females close to shore prior
to nesting are (a) sensing climatic changes, i.e. a
rain-bearing depression and/or a falling barometric
pressure, (b) absorbing cloacal fluid prior to nest-
ing and (c) absorbing body heat in the shallower
warmer water.

Although there is a seasonal difference between
the nesting behaviour of C. longicollis as described
by Vestjens (1969), there appears to be no great
difference between the two species in the excavation
of the nest site, except for size. The nest size of
Pseiidemys scripta as described by Moll and Legler
(1971) is similar in size to that of C. obionga. The
egg chamber of C. longicollis is smaller than that
of C. obionga.

Burbidge (1967) states that C. obionga, C.
steindachneri and probably all other Chelidae, pos-
sess a pair of bladders opening laterally into the
cloaca in addition to the urinary bladder which
opens ventrally. Goode and Russell (1968) state
that Chelodina longicollis and C. expansa void
copious amounts of cloacal fluid during the exca-
vation of the nest site. C. expansa puddles its eggs
in the mud produced by the excretion of the cloacal
fluid. During this study it was impossible to deter-
mine when the cloacal fluid was voided during egg
laying as the tail is held tight and close to the
body while excavating the egg chamber. Cloacal
fluid analysed by Burbidge (1967) shows that it is
the same constituency as that of the lake water
from which the tortoise is collected.

Some difficulty was experienced in locating females
that were nesting, but it is evident from the few
samples obtained that larger females lay larger and

heavier eggs than smaller females (Table 6). The
average clutch size for the summer nesting period
was significantly lower than that of the spring
nesting period (Table 5). Due possibly to the intense
heat during the summer nesting period females
moved a much shorter distance than the females
moving to nest during the spring nesting period.
(Table 3).

Incubation times during this study varied from
210 days to 222 days, compared with 138 days for
C. longicollis, 342 days for C. expansa, and 75 days
for Emydura macquari. (Goode and Russell 1968).
Eggs laid in the spring nesting period hatch in 210
to 222 days and remain underground in an em-
bryonic position until they emerge. Eggs laid in the
summer nesting period take as long to incubate but
remain in the nest for a shorter period, and young
emerging at the same time (mid-August) as hatch-
lings from the spring nesting period. Reports by
amateur observers tend to support the findings of
this study that the young emerge about mid-August,
with slight variations depending on seasonal con-
ditions.

Acknowledgements

t thank Professor S. D. Bradshaw and Drs. D. H.
Edward, J. E. Kinnear, G. M. Storr, R. J. Whelan and
Mr. A. H. Burbidge for criticism of the manuscript.

References

Brattstrom, B. H. (1965). — Body temperature of reptiles.
Am. Mid. Nat., 73 : 376-422.

Burbidge, A. A. (1967). — The biology of the south west
Australian tortoises. Unpub. Ph.D. thesis.

Zoology Dept., University of W.A.

Carr, A. (1952). — Handbook of turtles. Cornell Univ.

Press. Ithaca 542p.

Carr. A. (1967). — So excellent a fishe. A natural history
of sea turtles. Natural History Press, Garden
City, New York, 248p.

Cogger, H. G. (1975). — Reptiles and Amphibians of Australia.

A. H. & A. W. Reed, Sydney.

Goode, J. (1967). — Freshwater tortoises of Australia and New
Guinea (in the family Chelidae). Lansdowne
Press, Melbourne.

Goode, J. and Russell, J. (1968).— Incubation of eggs of the
three species of Chelid tortoises and notes on
their embryological development. Aust. J. ZooL,
16 : 749-61.

Hendrickson, J. H. (1958).— The green sea turtle, Chelonia
mydas, (Linn.) in Malaya and Sarawak. Proc.
Zool. Soc. Lond., 130 : 455-535.

Loch J H (1950).— Notes on the Perak River Turtle. Malayan
’ Natur. J., 5 : 157-160.

Moll, E. O. & Legler, J. M. (1971).— The life history of
a neotropical slider turtle Pseiidemys scripta
(Schoepff), in Panama. Bull. L. A. County Mus.
Nat. Hist. Sc. No. 11.

Seddon, G. (1972).— Sense of Place. University of W.A. Press
Perth, W.A.

Vestjens, W. J. M. (1969).— Nesting, egg laying and hatching
of the snake-necked tortoise of Canberra, A.C.T.
Aust. Zool, 15 : 141-149.

W.A. Year Book (1973).— Govt. Print., W.A.

32

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Journal

of the

Royal Society of Western Australia

Volume 64 1981

Part 1

Contents

Page

Ecosystem theory and management. By A. R. Main . , .... I

Peripheral vegetation of Peel Inlet and Harvey Estuary, Western Australia. By

D. J. Backshal! and P. B. Bridgewater .... . .. . 5

Obituary. Leslie William Samuel . ... 12

Preliminary observations of behavioural thermoregulation in an elapid snake,
the dugite, Pseiidonaja affinis Gunther. By H. Saint Girons and S. D.
Bradshaw .... .... .... . . ... ... ... ... 13

The distribution of benthic macroflora in the Swan River estuary, Western

Australia. By Bruce M. Allender , . .. .. 17

Fish scales from the Permian of Western Australia. By N. W. Archbold 23

Observations on the breeding biology and behaviour of the long-necked

tortoise, Chelodina ohlonga. By B. T. Clay .... .... .... .... 27

Editor: A. E. Cockbain

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